Display apparatus

ABSTRACT

A display apparatus includes a display panel configured to display an image and a sound generating device on a rear surface of the display panel. The sound generating device is configured to vibrate the display panel to generate sound. The sound generating device includes a first structure and a first passivation layer on one side of the first structure, at least a portion of the first passivation layer having a non-flat shape.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to Korean PatentApplication No. 10-2018-0139194 filed on Nov. 13, 2018, the entirety ofwhich is hereby incorporated by reference.

BACKGROUND Technical Field

The present disclosure relates to a display apparatus, and moreparticularly, to a display apparatus configured to vibrate a displaypanel to generate sound.

Discussion of the Related Art

Recently, as society advances toward an information-oriented society,the field of display apparatuses for visually displaying an electricalinformation signal has rapidly advanced. Consequently, various displayapparatuses having excellent performance, such as thinness, lightweight, and low power consumption, are being developed.

Examples of the display apparatuses may include liquid crystal display(LCD) apparatuses, field emission display (FED) apparatuses, organiclight emitting display apparatuses, light emitting diode displayapparatuses, quantum dot light emitting display apparatuses, and microlight emitting diode display apparatuses.

The LCD apparatuses include an array substrate including a thin filmtransistor (TFT), an upper substrate including a color filter and/or ablack matrix, and a liquid crystal layer between the array substrate andthe upper substrate. The LCD apparatuses are apparatuses in which analignment state of the liquid crystal layer is adjusted with an electricfield generated between two electrodes provided in a pixel area, and atransmittance of light is adjusted based on the alignment state, therebydisplaying an image.

The organic light emitting display apparatuses, which are self-emittingdevices, have low power consumption, a fast response time, high emissionefficiency, excellent luminance, and a wide viewing angle.

Display apparatuses may include a display panel which displays an imageand a sound device which outputs a sound along with an image. In thedisplay apparatuses, a sound generated by the sound device travelstoward a rear surface of the display panel or toward a region under thedisplay panel, instead of toward a front surface of the display panel.Therefore, sound quality is degraded due to interference of a soundreflected from a wall or a floor. For this reason, it is difficult toprovide a clear sound from the sound device without hindering animmersion experience of a user.

Moreover, in a case where a speaker included in a set apparatus such asa television (TV), a computer monitor, a notebook computer, or a desktoppersonal computer (PC) is provided, the speaker occupies a certainspace, and due to this, the design and space disposition of the setapparatus are limited.

A speaker applied to display apparatuses may be, for example, anactuator including a magnet and a coil. However, when the actuator isapplied to the display apparatuses, a thickness thereof is thick.Piezoelectric elements that enable a thin thickness to be implementedare attracting much attention. Since the piezoelectric elements have afragile characteristic, the piezoelectric elements are easily damaged byan external impact, and due to this, the reliability of soundreproduction is low.

SUMMARY

Accordingly, embodiments of the present disclosure are directed to adisplay apparatus that substantially obviates one or more of theproblems due to limitations and disadvantages of the related art.

Therefore, the present inventors have recognized the above-describedproblems and have invented a display apparatus having a new structure,which includes a sound generating device having a thin thickness forrealizing a thin thickness of the display apparatus and decreases aninfluence of an external impact.

An aspect of the present disclosure is to provide a display apparatusincluding a sound generating device for decreasing an influence of anexternal impact and enhancing a sound characteristic.

Additional features and aspects will be set forth in the descriptionthat follows, and in part will be apparent from the description, or maybe learned by practice of the inventive concepts provided herein. Otherfeatures and aspects of the inventive concepts may be realized andattained by the structure particularly pointed out in the writtendescription, or derivabel therefrom, and the claims hereof as well asthe appended drawings.

To achieve these and other aspects of the inventive concepts as embodiedand broadly described herein, a display apparatus comprises a displaypanel configured to display an image and a sound generating device on arear surface of the display panel, the sound generating device beingconfigured to vibrate the display panel to generate sound, wherein thesound generating device includes a first structure and a firstpassivation layer on one side of the first structure, at least a portionof the first passivation layer having a non-flat shape.

In another aspect, a display apparatus comprises a display panelincluding a display area configured to display an image and anon-display area surrounding the display area and a sound generatingdevice on a rear surface of the display panel, the sound generatingdevice being configured to vibrate the display panel to generate sound,wherein the sound generating device includes a first structure includinga first part having a piezoelectric characteristic and a second partbetween adjacent first parts to have flexibility and a passivation layeron or under the first structure, the passivation layer including aplurality of concave portions.

A display apparatus according to an embodiment of the present disclosuremay include the sound generating device including the first structureand the second structure, and thus, may secure the impact resistance andflexibility of the sound generating device. Accordingly, a displayapparatus having an excellent vibration characteristic and an excellentsound characteristic may be provided.

Moreover, the display apparatus according to an embodiment of thepresent disclosure may include the sound generating device including thefirst structure and the second structure, and thus, may decrease aninfluence of an external impact. Accordingly, a sound generating devicewith enhanced flexibility and sound pressure level may be provided, andthus, may be applied to a flexible display apparatus.

Other systems, methods, features and advantages will be, or will become,apparent to one with skill in the art upon examination of the followingfigures and detailed description. It is intended that all suchadditional systems, methods, features and advantages be included withinthis description, be within the scope of the present disclosure, and beprotected by the following claims. Nothing in this section should betaken as a limitation on those claims. Further aspects and advantagesare discussed below in conjunction with embodiments of the disclosure.It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexamples and explanatory and are intended to provide further explanationof the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, that may be included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain various principles of thedisclosure.

FIG. 1 illustrates a display apparatus including a sound generatingdevice according to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1.

FIG. 3 illustrates a sound generating device according to an embodimentof the present disclosure.

FIGS. 4A and 4B illustrate for describing an influence of an externalimpact on a sound generating device.

FIGS. 5A to 5C illustrate a display apparatus according to an embodimentof the present disclosure.

FIGS. 6A to 6C illustrate a display apparatus according to an embodimentof the present disclosure.

FIG. 7 illustrates an example of a first structure of a sound generatingdevice according to an embodiment of the present disclosure.

FIGS. 8A to 8C illustrate another example of a first structure of asound generating device according to an embodiment of the presentdisclosure.

FIGS. 9A and 9B illustrate another example of a first structure of asound generating device according to an embodiment of the presentdisclosure.

FIGS. 10A and 10B illustrate another example of a first structure of asound generating device according to an embodiment of the presentdisclosure.

FIG. 11 illustrates a display apparatus according to an embodiment ofthe present disclosure.

FIG. 12 illustrates a sound generating device according to an embodimentof the present disclosure.

FIGS. 13A and 13B illustrate a display apparatus including a soundgenerating device according to an embodiment of the present disclosure.

FIG. 14 illustrates a sound generating device according to an embodimentof the present disclosure.

FIGS. 15A to 15C illustrate a display apparatus including a soundgenerating device according to an embodiment of the present disclosure.

FIG. 16 illustrates a sound generating device according to an embodimentof the present disclosure.

FIG. 17 illustrates a display apparatus including a sound generatingdevice according to an embodiment of the present disclosure.

FIG. 18 illustrates a sound generating device according to an embodimentof the present disclosure.

FIGS. 19A and 19B illustrate a display apparatus including a soundgenerating device according to an embodiment of the present disclosure.

FIG. 20 illustrates a sound output characteristic of a sound generatingdevice according to an embodiment of the present disclosure.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals should be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary embodiments of thepresent disclosure, examples of which may be illustrated in theaccompanying drawings. In the following description, when a detaileddescription of well-known functions or configurations related to thisdocument is determined to unnecessarily cloud a gist of the inventiveconcept, the detailed description thereof will be omitted. Theprogression of processing steps and/or operations described is anexample; however, the sequence of steps and/or operations is not limitedto that set forth herein and may be changed as is known in the art, withthe exception of steps and/or operations necessarily occurring in aparticular order. Like reference numerals designate like elementsthroughout. Names of the respective elements used in the followingexplanations are selected only for convenience of writing thespecification and may be thus different from those used in actualproducts.

Advantages and features of the present disclosure, and implementationmethods thereof will be clarified through following embodimentsdescribed with reference to the accompanying drawings. The presentdisclosure may, however, be embodied in different forms and should notbe construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the present disclosureto those skilled in the art. Further, the present disclosure is onlydefined by scopes of claims.

A shape, a size, a ratio, an angle, and a number disclosed in thedrawings for describing embodiments of the present disclosure are merelyan example, and thus, the present disclosure is not limited to theillustrated details. Like reference numerals refer to like elementsthroughout. In the following description, when the detailed descriptionof the relevant known function or configuration is determined tounnecessarily obscure the important point of the present disclosure, thedetailed description will be omitted. In a case where “comprise,”“have,” and “include,” described in the present specification are used,another part may be added unless “only” is used. The terms of a singularform may include plural forms unless referred to the contrary.

In construing an element, the element is construed as including an errorrange although there is no explicit description.

In describing a position relationship, for example, when a positionrelation between two parts is described as “on,” “over,” “under,” and“next,” one or more other parts may be disposed between the two partsunless “just” or “direct(ly)” is used.

In describing a time relationship, for example, when the temporal orderis described as “after,” “subsequent,” “next,” and “before,” a casewhich is not continuous may be included unless “just” or “direct(ly)” isused.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure.

In describing the elements of the present disclosure, terms such as“first,” “second,” “A,” “B,” “(a),” “(b),” etc., may be used. Such termsare used for merely discriminating the corresponding elements from otherelements and the corresponding elements are not limited in theiressence, sequence, or precedence by the terms. It will be understoodthat when an element or layer is referred to as being “on” or “connectedto” another element or layer, it can be directly on or directlyconnected to the other element or layer, or intervening elements orlayers may be present. Also, it should be understood that when oneelement is disposed over or under another element, this may denote acase where the elements are disposed to directly contact each other, butmay denote that the elements are disposed without directly contactingeach other.

The term “at least one” should be understood as including any and allcombinations of one or more of the associated listed elements. Forexample, the meaning of “at least one of a first element, a secondelement, and a third element” denotes the combination of all elementsproposed from two or more of the first element, the second element, andthe third element as well as the first element, the second element, orthe third element.

Features of various embodiments of the present disclosure may bepartially or overall coupled to or combined to each other, and may bevariously inter-operated to each other and driven technically as thoseskilled in the art can sufficiently understand. The embodiments of thepresent disclosure may be carried out independently from each other, ormay be carried out together in co-dependent relationship.

In the present disclosure, examples of a display apparatus may include anarrow-sense display apparatus such as an organic light emitting display(OLED) module or a liquid crystal module (LCM) including a display paneland a driver for driving the display panel. Also, examples of thedisplay apparatus may include a set device (or a set apparatus) or a setelectronic device (or a set electronic apparatus) such as a notebookcomputer, a television (TV), a computer monitor, an equipment apparatusincluding an automotive apparatus or another type apparatuses forvehicles, or a mobile electronic apparatus such as a smartphone or anelectronic pad, which is a complete product (or a final product)including an LCM or an OLED module.

Therefore, in the present disclosure, examples of the display apparatusmay include a narrow-sense display apparatus itself, such as an LCM oran OLED module, and a set apparatus which is a final consumer apparatusor an application product including the LCM or the OLED module.

In some embodiments, an LCM or an OLED module including a display paneland a driver may be referred to as a narrow-sense display apparatus, andan electronic device which is a final product including an LCM or anOLED module may be referred to as a set device. For example, thenarrow-sense display apparatus may include a display panel, such as anLCD or an OLED, and a source printed circuit board (PCB) that is acontroller for driving the display panel. The set device may furtherinclude a set PCB that is a set controller electrically connected to thesource PCB to overall control the set device.

A display panel applied to an embodiment of the present disclosure mayuse any type of display panel, such as a liquid crystal display panel,an organic light emitting diode (OLED) display panel, and anelectroluminescent display panel, but is not limited to a specificdisplay panel that is vibrated by a sound generation device according toan embodiment of the present disclosure to output a sound. Also, a shapeor a size of a display panel applied to a display apparatus according toan embodiment of the present disclosure is not limited.

For example, if the display panel is the liquid crystal display panel,the display panel may include a plurality of gate lines, a plurality ofdata lines, and a plurality of pixels respectively provided in aplurality of pixel areas defined by intersections of the gate lines andthe data lines. Also, the display panel may include an array substrateincluding a thin film transistor (TFT), which is a switching element foradjusting a light transmittance of each of the plurality of pixels, anupper substrate including a color filter and/or a black matrix, and aliquid crystal layer between the array substrate and the uppersubstrate.

Moreover, if the display panel is the organic light emitting displaypanel, the display panel may include a plurality of gate lines, aplurality of data lines, and a plurality of pixels respectively providedin a plurality of pixel areas defined by intersections of the gate linesand the data lines. Also, the display panel may include an arraysubstrate including a TFT which is an element for selectively applying avoltage to each of the pixels, an organic light emitting device layer onthe array substrate, and an encapsulation substrate disposed on thearray substrate to cover the organic light emitting device layer. Theencapsulation substrate may protect the TFT and the organic lightemitting device layer from an external impact and may prevent water oroxygen from penetrating into the organic light emitting device layer.Also, a layer provided on the array substrate may include an inorganiclight emitting layer (for example, a nano-sized material layer, aquantum dot, or the like). As another example, the layer provided on thearray substrate may include a micro light emitting diode.

The display panel may further include a backing such as a metal plateattached to the display panel. However, embodiments are not limited tothe metal plate, and the display panel may include another structure.

In the present disclosure, the display panel may be applied to vehiclesas a user interface module such as a central control panel forautomobiles. For example, the display panel may be provided betweenoccupants sitting on two front seats in order for a vibration of thedisplay panel to be transferred to the inside of a vehicle. Therefore,an audio experience in a vehicle is improved in comparison with a casewhere speakers are disposed on interior sides of the vehicle.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings.

FIG. 1 illustrates a display apparatus including a sound generatingdevice according to an embodiment of the present disclosure. FIG. 2 is across-sectional view taken along line I-I′ of FIG. 1.

With reference to FIG. 1, the display apparatus 10 may include a displaypanel 100, which displays an image, and a sound generating device 200which is disposed on a rear surface of the display panel 100 andvibrates the display panel 100 to generate sound. For example, the soundgenerating device 200 may directly vibrate the display panel 100 tooutput sound toward a forward region in front of the display panel 100.

The display panel 100 may include a display area AA which displays animage and a non-display area which surrounds the display area AA. Thenon-display area may include a bending area BA. The bending area BA maybe bent to form a curved surface.

The display panel 100 may display an image and may be implemented as anytype of display panel, such as a liquid crystal display panel, anorganic light emitting diode (OLED) display panel, an electroluminescentdisplay panel, etc. The display panel 100 may vibrate based on avibration of the sound generating device 200 to output a sound.

According to an embodiment, the display panel 100 may display an imagein a type such as a top emission type, a bottom emission type, or a dualemission type, based on a structure of a pixel array layer including ananode electrode, a cathode electrode, and an organic compound layer. Inthe top emission type, visible light emitted from the pixel array layermay be irradiated onto a region in front of a base substrate to allow animage to be displayed. In the bottom emission type, the visible lightemitted from the pixel array layer may be irradiated onto a rearwardregion behind the base substrate to allow an image to be displayed.

Moreover, the sound generating device 200 may generate a sound by usingthe display panel 100 as a vibration plate. The sound generating device200 may be referred to as an “actuator,” an “exciter,” or a“transducer,” but embodiments are not limited thereto. For example, thesound generating device 200 may be a sound device for outputting a soundaccording to an electrical signal.

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1.

With reference to FIG. 2, the display apparatus 10 may include the soundgenerating device 200 and a supporting member 300.

The supporting member 300 may support one or more of a rear surface anda side surface of the display panel 100. Also, the sound generatingdevice 200 may be fixed to the supporting member 300.

The supporting member 300 may be, for example, a cover bottom. Forexample, the supporting member 300 may include a middle cabinet whichmay be coupled or connected to a cover bottom to surround the sidesurface of the display panel 100 and accommodates one edge or peripheryof the display panel 100 to support the display panel 100. For example,the middle cabinet may include a sideways-T(┤)-shaped cross-sectionalsurface (or a T-shape having a 90-degree angle). The supporting member300 may include the cover bottom, or may include the cover bottom andthe middle cabinet, but embodiments are not limited thereto. Forexample, the supporting member 300 may include a structure that supportsthe rear surface or the side surface of the display panel 100.

Moreover, the supporting member 300 may be a plate member that may beprovided on the rear surface of the display panel 100 or the wholedisplay panel 100. For example, the supporting member 300 may cover thewhole rear surface of the display panel 100 so as to be spaced apartfrom the rear surface. Also, the supporting member 300 may have a plateshape formed of a glass material, a metal material, or a plasticmaterial. Here, an edge or a sharp corner of the supporting member 300may have a tetragonal (e.g., quadrilateral) shape or a curved shape,e.g., through a chamfer process or a corner rounding process. Accordingto an embodiment of the present disclosure, the supporting member 300including the glass material may include sapphire glass. For example,the supporting member 300 including the metal material may include oneor more of aluminum (Al), an Al alloy, a magnesium (Mg) alloy, and aniron (Fe)-nickel (Ni) alloy. As another example, the supporting member300 may have a stacked structure including a glass plate and a metalplate, in which the metal plate may have a thickness relatively thinnerthan the glass plate and the glass plate may face the rear surface ofthe display panel 100. For example, a rear surface of the displayapparatus 10 may be used as a mirror surface due to the metal plate.

Moreover, in the present disclosure, the supporting member 300 may bereferred to as a “cover bottom,” a “plate bottom,” a “back cover,” a“base frame,” a “metal frame,” a “metal chassis,” a “chassis base,” oran “m-chassis.” Therefore, the supporting member 300 may be a supporterfor supporting the display panel 100 and may be implemented as any typeof frame or plate structure on the rear surface of the displayapparatus.

An adhesive member 410 may be disposed in an edge or periphery of thedisplay panel 100 and the supporting member 300. For example, theadhesive member 410 may be between the rear surface of the display panel100 and an upper surface of the supporting member 300. The adhesivemember 410 may attach the display panel 100 to the supporting member300. Also, the adhesive member 410 may include a double-sided tape, asingle-sided tape, an adhesive, a bond, and/or the like, but embodimentsare not limited thereto.

FIG. 3 illustrates a display apparatus according to an embodiment of thepresent disclosure.

With reference to FIG. 3, the display apparatus 10 may include a displaypanel 100 and a sound generating device 20. The sound generating device20 may include a first structure 240, a plurality of electrodes 211 and212, and a plurality of passivation layers 15 and 16. The firststructure 240 may include an inorganic material part 24 a and an organicmaterial part 24 b.

When a sound generating device is disposed on a rear surface of adisplay panel, there is a problem where a thickness of a displayapparatus is thickened as a thickness of the sound generating device isthickened. To solve the problem, a piezoelectric device having a thinthickness may be applied, but since the piezoelectric device isvulnerable to an external impact, the piezoelectric device is fragile,and due to this, has a problem where it is difficult to output a desiredsound. Therefore, to apply a sound generating device to a display panel,an external impact should not be applied to the sound generating device.Therefore, the present inventors have performed an impact experimentafter a sound generating device is applied to a display apparatus. Thiswill be described below with reference to FIGS. 4A and 4B.

FIGS. 4A and 4B illustrate for describing an influence of an externalimpact on a sound generating device.

An external impact test performed on a display apparatus may use, forexample, a ball drop test. The ball drop test may be a test where asound generating module impacted and a display panel including the sameare fixed to a drop position, and by allowing an iron bead having aweight of 100 g or 1,000 g to freely fall at a distance of 1 m in avertical direction, the display performance of an impacted display panelafter the ball drop test is compared with the display performance of animpacted display panel before the ball drop test. In a case whichdesires to check a quantitative control issue and a secondary collisionissue in association with free fall with respect to a finished displayapparatus to which a display panel and a sound generating module areapplied, a free falling impact test with reliability added thereto maybe used. The free falling impact test may be a test where, in a statewhere a finished display apparatus is applied, a falling target istransported by a certain height, for example 1 meter or more, and isfreely fallen on a falling floor surface, and by using various sensors,a degree of damage of a freely fallen target is determined. However,embodiments are not limited thereto, and another method may be used asan impact test performed on a display panel and a sound generatingmodule.

FIG. 4A illustrates a comparative example where a piezoelectric deviceis applied to a display apparatus. FIG. 4B illustrates an example whereFIG. 3 is applied.

With reference to FIG. 4A, a plurality of electrodes 211 and 212 may berespectively disposed over and under piezoelectric ceramic which is apiezoelectric device P. The electrode 211 may be a positive (+)electrode, and the electrode 212 may be a negative (−) electrode. Ayoung's modulus of the piezoelectric device P may be high, and due tothis, when an external impact (illustrated by an arrow) is applied tothe piezoelectric device P, the piezoelectric device P may be broken. Aportion broken by an impact applied thereto is illustrated by “A”. Forexample, the young's modulus of the piezoelectric device P may be 50 GPaor more. When an external impact is applied to a display apparatus, ascreen of the display apparatus may be displayed, but since apiezoelectric device is broken, a sound may not be reproduced.

With reference to FIG. 4B, a plurality of electrodes 211 and 212 may berespectively disposed over and under a first structure 240 of a soundgenerating device. The electrode 211 may be a positive (+) electrode,and the electrode 212 may be a negative (−) electrode. For example, ayoung's modulus of the first structure 240 may be 50 GPa or less. Theyoung's modulus of the first structure 240 may be less than a young'smodulus of a piezoelectric device, the first structure 240 may have acharacteristic robust to an impact. For example, an impact may beabsorbed by an organic material part 24 b included in the firststructure 240, but an inorganic material part 24 a may be partiallybroken (illustrated by “A”). Due to this, the performance orcharacteristic of the sound generating device may be reduced.

Therefore, the present inventors have implemented a sound generatingdevice which vibrates a display panel to output a desired sound,decreases an impact applied thereto from the outside, and enhances asound pressure level. This will be described below with reference toFIGS. 5 to 20.

FIGS. 5A to 5C illustrates a display apparatus according to anembodiment of the present disclosure.

With reference to FIG. 5A, a display apparatus 20 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 200. The sound generating device 200 mayinclude a first structure 240, a plurality of electrodes 211 and 212,and a plurality of passivation layers 201 and 202. The first structure240 may include a first part 24 a and a second part 24 b betweenadjacent first parts 24 a. The first part 24 a may include an inorganicmaterial part, and the second part 24 b may include an organic materialpart.

The first part 24 a of the first structure 240 may have piezoelectricproperties. Therefore, the inorganic material part may be formed of aceramic-based electrically active material for realizing a highvibration. For example, the inorganic material part may be formed of aceramic-based material for realizing a high vibration. As anotherexample, the inorganic material part may be formed of piezoelectricceramic having a perovskite crystalline structure. The perovskitecrystalline structure may be a plate-shaped structure which has apiezoelectric effect, an inverse piezoelectric effect, and alignmentproperties. The perovskite crystalline structure may be represented byan ABO₃ chemical formula, wherein A includes a divalent metal elementand B includes a tetravalent metal element. As another example, theinorganic material part may include one or more of lead (Pb), zirconium(Zr), titanium (Ti), zinc (Zn), nickel (Ni), and niobium (Nb), butembodiments are not limited thereto. As another example, the inorganicmaterial part may include a PZT-based material including lead (Pb),zirconium (Zr), and titanium (Ti) and a PZNN-based material includinglead (Pb), zinc (Zn), nickel (Ni), and niobium (Nb), but embodiments arenot limited thereto. Also, the inorganic material part may include atleast one of perovskite (CaTiO₃), barium titanate (BaTiO₃), andstrontium titanate (SrTiO₃) including no Pb, but embodiments are notlimited thereto. As another example, the inorganic material part mayinclude piezoelectric ceramic having a wurtzite crystalline structure.For example, the inorganic material part may include at least one ofaluminum nitride (AlN), silver iodide (AgI), zinc oxide (ZnO), cadmiumsulfide (CdS), cadmium selenide (CdSe), silicon carbide (α-SiC),gallium(III) nitride (GaN), and boron nitride (BN), but embodiments arenot limited thereto.

The second part 24 b may be configured to fill a space between adjacentfirst parts 24 a. For example, the second part 24 b may be formed of anorganic material and may be disposed to fill a space between adjacentinorganic material parts which are first parts 24 a. Alternatively, aplurality of first parts 24 a and a plurality of second parts 24 b maybe alternately disposed. For example, an inorganic material part whichis the first part 24 a and an organic material part which is the secondpart 24 b may be alternately disposed.

The second part 24 b of the first structure 240 may have flexibility.The organic material part may include at least one of an organicpiezoelectric material and an organic non-piezoelectric material. Whenthe organic material part includes the organic piezoelectric material,the organic material part may be formed of a polymer having flexibilityinstead of ceramic, and thus, may absorb an impact applied to theinorganic material part and may release a stress concentrating on theinorganic material part, thereby enhancing the durability and impactresistance of the first structure 240 and providing a certain level ofpiezoelectric characteristic. The organic piezoelectric material may bea material having an electrically active characteristic. For example,the organic piezoelectric material may include at least one of PVDF,β-PVDF, and PVDF-TrFE, but embodiments are not limited thereto. Theorganic non-piezoelectric material may include at least one of anacrylic polymer, a silicon-based polymer, and an epoxy-based polymer,but embodiments are not limited thereto.

A ceramic plate including an inorganic material part which is the firstpart 24 a may be formed and may be diced, and then, an organic materialpart which is the second part 24 b may be filled into diced portions,thereby forming the first structure 240. A method of dicing theinorganic material part may use at least one of scribing, blade dicing,laser cutting, stealth dicing, and thermal laser separation (TLS), butembodiments are not limited thereto. As another example, the firststructure 240 may be formed by filling the organic material part intothe inorganic material part which is formed in a fiber form and aligned,but embodiments are not limited thereto.

A first electrode 211 may be disposed over the first structure 240, anda second electrode 212 may be disposed under the first structure 240.The first electrode 211 and the second electrode 212 may apply a voltageto the first structure 240. For example, the first electrode 211 may bea negative (−) electrode, and the second electrode 212 may be a positive(+) electrode. As another example, the first electrode 211 may be apositive (+) electrode, and the second electrode 212 may be a negative(−) electrode. For example, the first electrode 211 and the secondelectrode 212 may include one or more of carbon (C), palladium (Pd),iron (Fe), tin (Sn), aluminum (Al), nickel (Ni), platinum (Pt), gold(Au), silver (Ag), copper (Cu), titanium (Ti), and molybdenum (Mo), oran alloy thereof, but embodiments are not limited thereto. For example,the first electrode 211 and the second electrode 212 may include indiumtin oxide (ITO) or a molybdenum-titanium alloy (a Mo—Ti alloy), butembodiments are not limited thereto.

When an alternating current (AC) voltage is applied to the firstelectrode 211 and the second electrode 212 of the sound generatingdevice 200, the first structure 240 may alternately and repeatedlyexpand and contract, thereby generating a vibration based on a bendingphenomenon where a bending direction is alternately changed. The displaypanel 100 may vibrate based on the generated vibration to generate asound SW. For example, the sound generating device 200 may directlyvibrate the display panel 100 to output the sound SW to a forward regionin front of the display panel 100. The display panel 100 may vibratewith kinetic energy based on polarization which is performed in adirection vertical to the display panel 100. Therefore, polarizationperformed in a vector direction except the direction vertical to thedisplay panel 100 may be lost. A whole vibration of the sound generatingdevice 200 may be affected by summated energy in the vector directionvertical to the display panel 100, and thus, a polarization direction(illustrated by an arrow) of the first structure 240 may be a directionvertical to the display panel 100.

A first passivation layer 201 may be disposed over the first electrode211, and a second passivation layer 202 may be disposed under the secondelectrode 212. The first passivation layer 201 and the secondpassivation layer 202 may be formed of polyimide, but are not limitedthereto. When an external impact is applied, the first passivation layer201 and the second passivation layer 202 may protect the first structure240. For example, at least a portion of the first passivation layer 201and the second passivation layer 202 may have a non-flat shape. Thefirst passivation layer 201 and the second passivation layer 202 may beprovided to have a shape corresponding to the first part 24 a or thesecond part 24 b. For example, as described with reference to FIG. 4B,when an external impact is applied, an impact applied to the first part24 a in the first structure 240 may be greater than an impact applied tothe second part 24 b, and thus, the first passivation layer 201 and thesecond passivation layer 202 may be provided to have a shapecorresponding to the first part 24 a. The first passivation layer 201may include a plurality of concave portions 201 a, and the plurality ofconcave portions 201 a may be disposed to correspond to the first part24 a. The second passivation layer 202 may include a plurality ofconcave portions 202 a, and the plurality of concave portions 202 a maybe disposed to correspond to the first part 24 a. Since the firstpassivation layer 201 or the second passivation layer 202 includes theplurality of concave portions 201 a or the plurality of concave portions202 a, air around the sound generating device 200 may vibrate to amplifya sound, and thus, a sound pressure level of the sound generating device200 may be enhanced, thereby decreasing an impact applied to the soundgenerating device 200 when an external impact is applied. A degree ofamplification of a sound may vary based on a shape of the firstpassivation layer 201 and the second passivation layer 202, and forexample, a shape of the first passivation layer 201 and the secondpassivation layer 202 may be a triangular (e.g., quadrilateral) shape, atetragonal shape, a spherical shape, a circular shape, an oval (e.g.,elliptical) shape, or the like. However, the shape is not limitedthereto. When the first passivation layer 201 and the second passivationlayer 202 has an oval shape, a sound may be more amplified. The firstpassivation layer 201 and the second passivation layer 202 may beimplemented to have an embossing shape including a plurality of concaveportions using an embossing roller, but embodiments are not limitedthereto.

With reference to FIG. 5B, a display apparatus 40 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 400. In comparison with FIG. 5A, in the soundgenerating device 400, a first part and a second part may be widelyprovided in the same area, and thus, a sound characteristic andflexibility may be further enhanced. The sound generating device 400 mayinclude a first structure 240, a plurality of electrodes 211 and 212,and a plurality of passivation layers (for example, first and secondpassivation layers) 401 and 402. The first passivation layer 401 may bedisposed over the first electrode 211, and the second passivation layer402 may be disposed under the second electrode 212. The firstpassivation layer 401 and the second passivation layer 402 may be formedof polyimide, but embodiments are not limited thereto. When an externalimpact is applied, the first passivation layer 401 and the secondpassivation layer 402 may protect the first structure 240. For example,at least a portion of the first passivation layer 401 and the secondpassivation layer 402 may have a non-flat shape. The first passivationlayer 401 and the second passivation layer 402 may have a shapecorresponding to a first part 24 a or a second part 24 b. For example,as described with reference to FIG. 4B, when an external impact isapplied, an impact applied to the first part 24 a included in the firststructure 240 may be greater than an impact applied to the second part24 b, and thus, the first passivation layer 401 and the secondpassivation layer 402 may have a shape corresponding to the first part24 a. The first passivation layer 401 may include a plurality of concaveportions 401 a, and the plurality of concave portions 401 a maycorrespond to at least two first parts 24 a and a second part 24 b. Forexample, the plurality of concave portions 401 a may correspond to atleast two first parts 24 a and a second part 24 b between the at leasttwo first parts 24 a. The second passivation layer 402 may include aplurality of concave portions 402 a, and the plurality of concaveportions 402 a may correspond to at least two first parts 24 a and asecond part 24 b. For example, the plurality of concave portions 402 amay correspond to at least two first parts 24 a and a second part 24 bbetween the at least two first parts 24 a. Since the first passivationlayer 401 or the second passivation layer 402 may include a plurality ofconcave portions, air around the sound generating device 400 may vibrateto amplify a sound, and thus, a sound pressure level of the soundgenerating device 400 may be enhanced, thereby decreasing an impactapplied to the sound generating device 400 when an external impact isapplied. A degree of amplification of a sound may vary based on a shapeof the first passivation layer 401 and the second passivation layer 402,and for example, a shape of the first passivation layer 401 and thesecond passivation layer 402 may be a triangular shape, a tetragonal(e.g., quadrilateral) shape, a spherical shape, a circular shape, anoval (e.g., elliptical) shape, or the like. However, the shape is notlimited thereto. When the first passivation layer 401 and the secondpassivation layer 402 has an oval (e.g., elliptical) shape, a sound maybe more amplified. The first passivation layer 401 and the secondpassivation layer 402 may be implemented to have an embossing shapeincluding a plurality of concave portions using an embossing roller, butembodiments are not limited thereto.

With reference to FIG. 5C, a display apparatus 45 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 450. The sound generating device 450 mayinclude a first structure 240, a plurality of electrodes 211 and 212,and a plurality of passivation layers (for example, first and secondpassivation layers) 451 and 452. The first passivation layer 451 may bedisposed over the first electrode 211, and the second passivation layer452 may be disposed under the second electrode 212. The firstpassivation layer 451 and the second passivation layer 452 may be formedof polyimide, but embodiments are not limited thereto. When an externalimpact is applied, the first passivation layer 451 and the secondpassivation layer 452 may protect the first structure 240. For example,at least a portion of the first passivation layer 451 and the secondpassivation layer 452 may have a non-flat shape. The first passivationlayer 451 and the second passivation layer 452 may have a shapecorresponding to a first part 24 a or a second part 24 b. For example,as described with reference to FIG. 4B, when an external impact isapplied, an impact applied to the first part 24 a in the first structure240 may be greater than an impact applied to the second part 24 b, andthus, the first passivation layer 451 and the second passivation layer452 may have a shape corresponding to the first part 24 a. The firstpassivation layer 451 may include a plurality of concave portions 451 a,and the plurality of concave portions 451 a may be disposed tocorrespond to at least two first parts 24 a and a second part 24 b. Forexample, the plurality of concave portions 451 a may be disposed tocorrespond to at least two first parts 24 a and a second part 24 bbetween the at least two first parts 24 a. The second passivation layer452 may include a plurality of concave portions 452 a, and the pluralityof concave portions 452 a may be disposed to correspond to at least twofirst parts 24 a and a second part 24 b. For example, the plurality ofconcave portions 452 a may be disposed to correspond to at least twofirst parts 24 a and a second part 24 b between the at least two firstparts 24 a. In a case where the plurality of concave portions of thefirst passivation layer 451 or the second passivation layer 452 areprovided to correspond to the at least two first parts 24 a and thesecond part 24 b, the first passivation layer 451 including theplurality of concave portions 451 a and the second passivation layer 452including the plurality of concave portions 452 a may be easilymanufactured. Since the first passivation layer 451 or the secondpassivation layer 452 may include a plurality of concave portions, airaround the sound generating device 450 may vibrate to amplify a sound,and thus, a sound pressure level of the sound generating device 450 maybe enhanced, thereby decreasing an impact applied to the soundgenerating device 450 when an external impact is applied. A degree ofamplification of a sound may vary based on a shape of the firstpassivation layer 451 and the second passivation layer 452, and forexample, a shape of the first passivation layer 451 and the secondpassivation layer 452 may be a triangular shape, a tetragonal (e.g.,quadrilateral) shape, a spherical shape, a circular shape, an oval(e.g., elliptical) shape, or the like. However, the shape is not limitedthereto. The first passivation layer 451 and the second passivationlayer 452 may be implemented to have an embossing shape including aplurality of concave portions using an embossing roller, but embodimentsare not limited thereto.

With reference to FIGS. 5A to 5C, an adhesive member may be furtherprovided between the first passivation layer 201, 401 and 451 and thefirst electrode 211, and an adhesive member may be further providedbetween the second passivation layer 202, 402 and 452 and the secondelectrode 212. The adhesive may be, for example, an acrylic adhesive, anepoxy-based adhesive, and a silicon-based adhesive, and a functionalgroup may be added to the adhesive to improve an adhesive force or amanufacturing process. However, embodiments are not limited thereto.Also, to improve an adhesive force to the passivation layer 201, 202,401, 402, 451, and 452 and/or enhance an elastic modulus suitable forthe first electrode 211 or the second electrode 212, the adhesive may beused in common or mixed, or a thickness of the adhesive may bedifferently adjusted. However, embodiments are not limited thereto.

FIGS. 6A to 6C illustrate a display apparatus according to an embodimentof the present disclosure.

With reference to FIG. 6A, a display apparatus 50 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 500. The sound generating device 500 mayinclude a first structure 240, a plurality of electrodes 211 and 212,and a plurality of passivation layers (for example, first and secondpassivation layers) 501 and 502. The first structure 240 and theelectrodes 211 and 212 are as described above with reference to FIGS. 5Ato 5C, and thus, their detailed descriptions are omitted. The firstpassivation layer 501 may be disposed over the first electrode 211, andthe second passivation layer 502 may be disposed under the secondelectrode 212. The first passivation layer 501 and the secondpassivation layer 502 may be formed of polyimide, but are not limitedthereto. When an external impact is applied, the first passivation layer501 and the second passivation layer 502 may protect the first structure240. For example, at least a portion of the first passivation layer 501and the second passivation layer 502 may have a non-flat shape. Forexample, as described with reference to FIG. 4B, when an external impactis applied, an impact applied to the first part 24 a included in thefirst structure 240 may be greater than an impact applied to the secondpart 24 b, and thus, the first passivation layer 501 and the secondpassivation layer 502 may be provided to have a shape corresponding tothe first part 24 a. For example, the first passivation layer 501 mayinclude a plurality of concave portions 501 a and a plurality of convexportions 501 b. The second passivation layer 502 may include a pluralityof concave portions 502 a and a plurality of convex portions 502 b. Theplurality of concave portions and the plurality of convex portions ofthe first passivation layer 501 and the second passivation layer 502 maybe arranged in zigzag. For example, the plurality of concave portions501 a of the first passivation layer 501 may be disposed to correspondto the first part 24 a, and the plurality of convex portions 501 b maybe disposed to correspond to the first part 24 a and the second portion24 b. For example, the plurality of concave portions 502 a of the secondpassivation layer 502 may be disposed to correspond to the first part 24a, and the plurality of convex portions 502 b may be disposed tocorrespond to the first part 24 a and the second portion 24 b. An airlayer of the plurality of convex portions 501 b and 502 b may preventthe first part 24 a from being damaged by an external impact or anexternal pressure and when a voltage is applied to the electrode, maysecure a space enabling the first part 24 a to vibrate, therebyenhancing a sound pressure level. Since the first passivation layer 501or the second passivation layer 502 includes the plurality of concaveportions or the plurality of convex portions, air around the soundgenerating device 500 may vibrate and may secure a vibration space, andthus, may amplify a sound to enhance a sound pressure level of the soundgenerating device 500, thereby decreasing an impact applied to the soundgenerating device 600 when an external impact is applied. A degree ofamplification of a sound may vary based on a shape of the firstpassivation layer 501 and the second passivation layer 502, and forexample, a shape of the first passivation layer 501 and the secondpassivation layer 502 may be a triangular shape, a tetragonal (e.g.,quadrilateral) shape, a spherical shape, a circular shape, an oval(e.g., elliptical) shape, or the like. However, the shape is not limitedthereto. The first passivation layer 501 and the second passivationlayer 502 may be implemented to have an embossing shape including aplurality of concave portions and a plurality of convex portions byusing an embossing roller, but embodiments are not limited thereto.

In FIG. 6A, the plurality of concave portions and the plurality ofconvex portions of the first passivation layer 501 and the secondpassivation layer 502 may be asymmetrically disposed. For example, theplurality of concave portions 501 a of the first passivation layer 501may correspond to the plurality of convex portions 502 b of the secondpassivation layer 502, and the plurality of convex portions 501 b of thefirst passivation layer 501 may correspond to the plurality of concaveportions 502 a of the second passivation layer 502. As another example,the plurality of concave portions and the plurality of convex portionsof the first passivation layer 501 and the second passivation layer 502may be symmetrically disposed. For example, the plurality of concaveportions 501 a of the first passivation layer 501 may correspond to theplurality of concave portions 502 a of the second passivation layer 502,and the plurality of convex portions 501 b of the first passivationlayer 501 may correspond to the plurality of convex portions 502 b ofthe second passivation layer 502.

With reference to FIG. 6B, a display apparatus 60 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 600. The sound generating device 600 mayinclude a first structure 240, a plurality of electrodes 211 and 212,and a plurality of passivation layers (for example, first and secondpassivation layers) 601 and 602. Comparing with FIG. 6A, in the soundgenerating device 600, a first part and a second part may be widelyprovided in the same area, and thus, a sound characteristic andflexibility may be more enhanced. The first structure 240 and theelectrodes 211 and 212 are as described above with reference to FIGS. 5Ato 5C, and thus, their detailed descriptions may be omitted. The firstpassivation layer 601 may be disposed over the first electrode 211, andthe second passivation layer 602 may be disposed under the secondelectrode 212. The first passivation layer 601 and the secondpassivation layer 602 may be formed of polyimide, but embodiments arenot limited thereto. When an external impact is applied, the firstpassivation layer 601 and the second passivation layer 602 may protectthe first structure 240. For example, at least a portion of the firstpassivation layer 601 and the second passivation layer 602 may have anon-flat shape. For example, as described with reference to FIG. 4B,when an external impact is applied, an impact applied to the first part24 a in the first structure 240 may be greater than an impact applied tothe second part 24 b, and thus, the first passivation layer 601 and thesecond passivation layer 602 may have a shape corresponding to the firstpart 24 a. For example, the first passivation layer 601 may include aplurality of concave portions 601 a and a plurality of convex portions601 b. The second passivation layer 602 may include a plurality ofconcave portions 602 a and a plurality of convex portions 602 b. Theplurality of concave portions and the plurality of convex portions ofthe first passivation layer 601 and the second passivation layer 602 maybe arranged in zigzag. The plurality of concave portions 601 a of thefirst passivation layer 601 may be disposed to correspond to at leasttwo first parts 24 a and a second part 24 b. For example, the pluralityof concave portions 601 a may be disposed to correspond to at least twofirst parts 24 a and the second part 24 b between the at least two firstparts 24 a. The plurality of convex portions 601 b of the firstpassivation layer 601 may be disposed to correspond to at least twofirst parts 24 a and a second part 24 b. For example, the plurality ofconvex portions 601 b may be disposed to correspond to at least twofirst parts 24 a and the second part 24 b disposed between the at leasttwo first parts 24 a. The plurality of concave portions 602 a of thesecond passivation layer 602 may be disposed to correspond to at leasttwo first parts 24 a and a second part 24 b. For example, the pluralityof concave portions 602 a may be disposed to correspond to at least twofirst parts 24 a and the second part 24 b disposed between the at leasttwo first parts 24 a. The plurality of convex portions 602 b of thesecond passivation layer 602 may be disposed to correspond to at leasttwo first parts 24 a and a second part 24 b. For example, the pluralityof convex portions 602 b may be disposed to correspond to at least twofirst parts 24 a and the second part 24 b disposed between the at leasttwo first parts 24 a. An air layer of the plurality of convex portions601 b and 602 b may prevent the first part 24 a from being damaged by anexternal impact or an external pressure and when a voltage is applied tothe electrode, may secure a space enabling the first part 24 a tovibrate, thereby enhancing a sound pressure level. Since the firstpassivation layer 601 or the second passivation layer 602 includes theplurality of concave portions or the plurality of convex portions, airaround the sound generating device 600 may vibrate and may secure avibration space, and thus, may amplify a sound to enhance a soundpressure level of the sound generating device 600, thereby decreasing animpact applied to the sound generating device 600 when an externalimpact is applied. A degree of amplification of a sound may vary basedon a shape of the first passivation layer 601 and the second passivationlayer 602, and for example, a shape of the first passivation layer 601and the second passivation layer 602 may be a triangular shape, atetragonal shape, a spherical shape, a circular shape, an oval shape, orthe like. However, the shape is not limited thereto. The firstpassivation layer 601 and the second passivation layer 602 may beimplemented to have an embossing shape including a plurality of concaveportions and a plurality of convex portions by using an embossingroller, but embodiments are not limited thereto.

In FIG. 6B, the plurality of concave portions and the plurality ofconvex portions of the first passivation layer 601 and the secondpassivation layer 602 may be asymmetrically disposed. For example, theplurality of concave portions 601 a of the first passivation layer 601may correspond to the plurality of convex portions 602 b of the secondpassivation layer 602, and the plurality of convex portions 601 b of thefirst passivation layer 601 may correspond to the plurality of concaveportions 602 a of the second passivation layer 602. As another example,the plurality of concave portions and the plurality of convex portionsof the first passivation layer 601 and the second passivation layer 602may be symmetrically disposed. For example, the plurality of concaveportions 601 a of the first passivation layer 601 may correspond to theplurality of concave portions 602 a of the second passivation layer 602,and the plurality of convex portions 601 b of the first passivationlayer 601 may correspond to the plurality of convex portions 602 b ofthe second passivation layer 602.

With reference to FIG. 6C, a display apparatus 65 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 650. The sound generating device 650 mayinclude a first structure 240, a plurality of electrodes 211 and 212,and a plurality of passivation layers (for example, first and secondpassivation layers) 651 and 652. The first structure 240 and theelectrodes 211 and 212 are as described above with reference to FIGS. 5Ato 5C, and thus, their detailed descriptions are omitted. The firstpassivation layer 651 may be disposed over the first electrode 211, andthe second passivation layer 652 may be disposed under the secondelectrode 212. The first passivation layer 651 and the secondpassivation layer 652 may be formed of polyimide, but are not limitedthereto. When an external impact is applied, the first passivation layer651 and the second passivation layer 652 may protect the first structure240. For example, at least a portion of the first passivation layer 651and the second passivation layer 652 may have a non-flat shape. Forexample, as described with reference to FIG. 4B, when an external impactis applied, an impact applied to the first part 24 a included in thefirst structure 240 may be greater than an impact applied to the secondpart 24 b, and thus, the first passivation layer 651 and the secondpassivation layer 652 may be provided to have a shape corresponding tothe first part 24 a. For example, the first passivation layer 651 mayinclude a plurality of concave portions 651 a and a plurality of convexportions 651 b. The second passivation layer 652 may include a pluralityof concave portions 652 a and a plurality of convex portions 652 b. Theplurality of concave portions and the plurality of convex portions ofthe first passivation layer 651 and the second passivation layer 652 maybe arranged in zigzag. The plurality of concave portions 651 a of thefirst passivation layer 651 may be disposed to correspond to at leasttwo first parts 24 a and a second part 24 b. For example, the pluralityof concave portions 651 a may be disposed to correspond to at least twofirst parts 24 a and a second part 24 b disposed between the at leasttwo first parts 24 a. The plurality of convex portions 651 b of thefirst passivation layer 651 may be disposed to correspond to at leastthree first parts 24 a and at least two second parts 24 b. For example,the plurality of convex portions 651 b may be disposed to correspond toat least three first parts 24 a and at least two seconds part 24 bdisposed between the at least three first parts 24 a. The plurality ofconvex portions 652 b of the second passivation layer 652 may bedisposed to correspond to at least three first parts 24 a and at leasttwo second parts 24 b. For example, the plurality of convex portions 652b may be disposed to correspond to at least three first parts 24 a andat least two second parts 24 b disposed between the at least three firstparts 24 a. The plurality of concave portions 652 a of the secondpassivation layer 652 may be disposed to correspond to at least twofirst parts 24 a and a second part 24 b. For example, the plurality ofconcave portions 652 a may be disposed to correspond to at least twofirst parts 24 a and the second part 24 b disposed between the at leasttwo first parts 24 a. In this case, the first passivation layer 651including the plurality of concave portions 651 a and the plurality ofconvex portions 651 b and the second passivation layer 652 including theplurality of concave portions 652 a and the plurality of convex portions652 b may be easily manufactured. An air layer of the plurality ofconvex portions 651 b and 652 b may prevent the first part 24 a frombeing damaged by an external impact or an external pressure and when avoltage is applied thereto, may secure a space enabling the first part24 a to vibrate, thereby enhancing a sound pressure level. Since thefirst passivation layer 651 or the second passivation layer 652 includesthe plurality of concave portions or the plurality of convex portions,air around the sound generating device 650 may vibrate and may secure avibration space, and thus, may amplify a sound to enhance a soundpressure level of the sound generating device 650, thereby decreasing animpact applied to the sound generating device 650 when an externalimpact is applied. A degree of amplification of a sound may vary basedon a shape of the first passivation layer 651 and the second passivationlayer 652, and for example, a shape of the first passivation layer 651and the second passivation layer 652 may be a triangular shape, atetragonal shape, a spherical shape, a circular shape, an oval shape, orthe like. However, the shape is not limited thereto. The firstpassivation layer 651 and the second passivation layer 652 may beimplemented to have an embossing shape including a plurality of concaveportions and a plurality of convex portions using an embossing roller,but embodiments are not limited thereto.

In FIG. 6C, the plurality of concave portions and the plurality ofconvex portions of the first passivation layer 651 and the secondpassivation layer 652 may be asymmetrically disposed. For example, theplurality of concave portions 651 a of the first passivation layer 651may correspond to the plurality of convex portions 652 b of the secondpassivation layer 652, and the plurality of convex portions 651 b of thefirst passivation layer 651 may correspond to the plurality of concaveportions 652 a of the second passivation layer 652. As another example,the plurality of concave portions and the plurality of convex portionsof the first passivation layer 651 and the second passivation layer 652may be symmetrically disposed. For example, the plurality of concaveportions 651 a of the first passivation layer 651 may correspond to theplurality of concave portions 652 a of the second passivation layer 652,and the plurality of convex portions 651 b of the first passivationlayer 651 may correspond to the plurality of convex portions 652 b ofthe second passivation layer 652.

With reference to FIGS. 6A to 6C, an adhesive member may be furtherprovided between the first passivation layer 501, 601 and 651 and thefirst electrode 211, and an adhesive member may be further providedbetween the second passivation layer 502, 602 and 652 and the firstelectrode 212. The adhesive may be, for example, an acrylic adhesive, anepoxy-based adhesive, and a silicon-based adhesive, and a functionalgroup may be added to the adhesive to improve an adhesive force or amanufacturing process. However, embodiments are not limited thereto.Also, in order to improve an adhesive force to the passivation layer501, 502, 601, 602, 651, and 652 and/or enhance an elastic modulussuitable for the first electrode 211 or the second electrode 212, theadhesive may be used in common or mixed, or a thickness of the adhesivemay be differently adjusted. However, embodiments are not limitedthereto.

FIG. 7 illustrates an example of a first structure of a sound generatingdevice according to an embodiment of the present disclosure.

With reference to FIG. 7, a first structure 240 of a sound generatingdevice may include a first part 24 a and a second part 24 b. The firststructure 240 may include the first part 24 a and the second part 24 bdisposed between adjacent first parts 24 a. The first part 24 a mayinclude an inorganic material part, and the second part 24 b may includean organic material part. The first part 24 a and the second part 24 bmay be disposed in parallel on the same plane. The second part 24 b maybe configured to fill a space between adjacent first parts 24 a. Forexample, the second part 24 b may be formed of an organic material partand may be disposed to fill a space between adjacent inorganic materialparts which are first parts 24 a. Alternatively, a plurality of firstparts 24 a and a plurality of second parts 24 b may be alternatelydisposed. For example, an inorganic material part which is the firstpart 24 a and an organic material part which is the second part 24 b maybe alternately disposed.

The first structure 240 of the sound generating device may include aplurality of diagonal patterns. The plurality of diagonal patterns maybe a plurality of line patterns having a certain width d1, and one ofthe plurality of line patterns may have a distance of certain width d2with respect to another pattern which is adjacent thereto and spacedapart therefrom. An organic material part configuring the second part 24b may be disposed between the plurality of line patterns to have thewidth d2 of an inorganic material part configuring the first part 24 a.The plurality of line patterns may be at least one of various patternssuch as a line pattern, a tetragonal pattern, a pentagonal pattern, anda honeycomb pattern, but embodiments are not limited thereto. Also, aplurality of circular patterns may have a circular shape, an oval shape,or a donut shape. The inorganic material part configuring the first part24 a may include a plurality of diagonal patterns or a plurality ofcircular patterns disposed apart from one another, and the organicmaterial part configuring the second part 24 b may be disposed to fill aspace between adjacent inorganic material parts configuring the firstpart 24 a.

FIGS. 8A to 8C illustrate another example of a first structure of asound generating device according to an embodiment of the presentdisclosure.

With reference to FIG. 8A, an inorganic material part of a width d1 andan organic material part of a width d2 of a sound generating deviceaccording to an embodiment of the present disclosure may be formed in aline pattern having the same width and may be alternately disposed.

With reference to FIG. 8B, an inorganic material part of a width d1 andof an organic material part of a width d2 of a sound generating deviceaccording to an embodiment of the present disclosure may be formed in aline pattern having different widths and may be alternately disposed.For example, a size of a first part 24 a may be the same as or differentfrom that of a second part 24 b. When a width of the inorganic materialpart is greater than that of the organic material part, flexibility ofthe sound generating device may be reduced, but the sound generatingdevice may have a high sound characteristic. Therefore, when a highsound characteristic is needed, a ratio of the inorganic material partmay be set to be higher than that of the organic material part. Asanother example, when the width of the inorganic material part is lessthan that of the organic material part, flexibility of the soundgenerating device may be good. Accordingly, when flexibility is needed,a ratio of the organic material part may be set to be higher than thatof the inorganic material part. In this case, for example, the soundgenerating device may be applied to a flexible display apparatus havinga curve or a high curvature.

With reference to FIG. 8C, an inorganic material part may be formed in aplurality of circular or oval patterns, and an organic material part maybe disposed between one inorganic material part formed in a circular oroval pattern and another inorganic material part which is adjacentthereto and is formed in a circular or oval pattern. A display apparatusincluding a sound generating device having a structure illustrated inFIG. 8C may be adjusted in order for a display panel to have variousshapes. Also, a plurality of circular, oval, or donut patterns may be afine pattern capable of corresponding to various shapes, and in a casewhich forms a circular, oval, or donut pattern, the pattern may bemodified to correspond to various deformations of a display panel.Accordingly, a display apparatus may be implemented to have variousshapes, and thus, a degree of freedom in design of a sound generatingdevice based on a shape of the display apparatus may be enhanced and thesound generating device may be applied to a flexible display apparatus.

FIGS. 9A and 9B are diagrams illustrating another example of a firststructure of a sound generating device according to an embodiment of thepresent disclosure.

FIG. 9A is a diagram illustrating an example where both ends of theinorganic material part and the organic material part of FIG. 8A arefolded upward. FIG. 9A will be described with reference to FIG. 8A forexample, and FIG. 8B may be identically applied thereto.

FIG. 9B is a diagram illustrating an example where the both ends of theinorganic material part and the organic material part of FIG. 9A arefolded downward. FIG. 9B will be described with reference to FIG. 8A forexample, and FIG. 8B may be identically applied thereto.

With reference to FIGS. 9A and 9B, in a sound generating deviceincluding an inorganic material part having a plurality of line patternsand an organic material part filling a space between adjacent inorganicmaterial parts, even when both ends disposed at ends in a lengthwisedirection of the plurality of line patterns are bent upward or downward,the inorganic material part may not be damaged or may not be reduced inperformance. Therefore, a display apparatus including the soundgenerating device which includes the inorganic material part having aplurality of line patterns and the organic material part filling a spacebetween adjacent inorganic material parts may be applied to a curveddisplay apparatus having a certain curvature, but embodiments are notlimited thereto and may be applied to a rollable display apparatus or abendable display apparatus. The bendable display apparatus may be, forexample, an edge bending display apparatus, but embodiments are notlimited thereto. As another example, the display apparatus may beapplied to a wearable display apparatus.

FIGS. 10A and 10B are diagrams illustrating another example of a firststructure of a sound generating device according to an embodiment of thepresent disclosure.

With reference to FIG. 10A, an inorganic material part may be formed ina plurality of triangular patterns, and an organic material part may bedisposed between one inorganic material part formed in a triangularpattern and another inorganic material part which is adjacent theretoand is formed in a triangular pattern. A display apparatus including asound generating device having a structure illustrated in FIG. 10A maybe adjusted in order for a display panel to have various shapes. Also, aplurality of triangular patterns may be a fine pattern capable ofcorresponding to various shapes, and in a case which finely forms atriangular pattern, the pattern may be modified to correspond to variousdeformations of a display panel.

Therefore, a display apparatus including a sound generating device whichincludes an inorganic material part formed in a plurality of polygonalpatterns or a plurality of circular patterns and an organic materialpart filling a space between adjacent inorganic material parts may bedeformed based on various deformations or bending thereof and may beprevented from being damaged by deformation or may be prevented frombeing reduced in performance. Therefore, the display apparatus includingthe sound generating device which includes the inorganic material partformed in a plurality of polygonal patterns or a plurality of circularpatterns and the organic material part filling a space between adjacentinorganic material parts may be applied to a curved display apparatushaving a certain curvature, but embodiments are not limited thereto andmay be applied to a rollable display apparatus or a bendable displayapparatus. The bendable display apparatus may be, for example, an edgebending display apparatus, but embodiments are not limited thereto. Asanother example, the display apparatus may be applied to a wearabledisplay apparatus.

FIG. 10B is a diagram for describing a method of manufacturing the soundgenerating device of FIG. 10A. Numbers of FIG. 10B represent order inwhich an inorganic material part having a plate or sheet shape is formedand diced.

In FIG. 10B, {circle around (1)} and {circle around (2)} respectivelyrepresent dicing performed in a widthwise direction and dicing performedin a lengthwise direction on an inorganic material part. In this case,the inorganic material part may move by a certain interval to correspondto a width or a shape of the inorganic material part which is set afterdicing is performed once, and dicing may be performed a plurality oftimes or may be performed once or more. In FIG. 10B, {circle around (3)}and {circle around (4)} represent dicing performed in a diagonaldirection on the inorganic material part. In this case, the inorganicmaterial part may move by a certain interval to correspond to a width ora shape of the inorganic material part which is set after dicing isperformed once, and dicing may be performed a plurality of times or maybe performed once or more. A method of dicing an inorganic material partis not limited thereto.

FIG. 11 is a diagram illustrating a display apparatus according to anembodiment of the present disclosure.

With reference to FIG. 11, a display apparatus 70 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 200. The sound generating device 200 mayinclude a first structure 240. The sound generating device 200 is asdescribed above with reference to FIGS. 5A to 10B, and thus, itsdetailed description is omitted. In FIG. 11, a sound generating deviceto which FIG. 5A is applied will be described, and moreover, the soundgenerating device of FIGS. 5B to 6C may be applied. With reference toFIG. 11, an example where the display apparatus 70 according to anembodiment of the present disclosure is folded inward from the displaypanel 100 is illustrated. An expansive stress which occurs when thedisplay apparatus 70 is folded inward from the display panel 100 may bereduced in the first structure 240. In a case where the sound generatingdevice 200 is applied to a foldable display apparatus, the display panel100 may have a certain curvature radius in one direction, and the soundgenerating device may be bent correspondingly to a curvature of thedisplay panel 100. As another example, the sound generating device 200according to an embodiment of the present disclosure may be applied to abendable or rollable display apparatus. Accordingly, a display apparatuswith enhanced flexibility and sound pressure level may be provided.

FIG. 12 is a diagram illustrating a sound generating device 700according to an embodiment of the present disclosure.

With reference to FIG. 12, the sound generating device 700 may include afirst structure 240 and a second structure 220. When a speaker having asingle layer of the second structure 220 is applied to a displayapparatus, there may be vertical polarization not sufficient to vibratethe display panel 100, and due to this, there may be a problem where itis difficult to secure a sound pressure characteristic suitable for aspeaker. Also, in a case where a speaker having a single layer of thefirst structure 240 is applied to a display apparatus, since it ispossible to secure a sound characteristic suitable for a speaker bygenerating a sufficient vibration in a direction vertical to the firststructure 240 but a portion having the piezoelectric properties of thefirst structure 240 is aligned in a horizontal direction with respect toa widthwise direction of the display panel 100, it is difficult to havea flexible characteristic other than a vertical direction with respectto an alignment direction, and it is difficult to secure an appropriateflexible characteristic in the vertical direction. In a case where thefirst structure 240 is formed of several layers or the second structure220 is formed of several layers so as to secure a sufficient vibrationcapable of having a sound pressure characteristic and improve theflexibility of a speaker, a thickness of the speaker is thickened, anddue to this, the display panel 100 is thickened.

For example, the second structure 220 may be disposed over the firststructure 240. However, embodiments are not limited thereto, and thefirst structure 240 may be disposed over the second structure 220. Thesecond structure 220 may be formed of a polymer piezoelectric material.For example, the second structure 220 may include a piezoelectricmaterial 22 b included in a polymer matrix 22 a. The piezoelectricmaterial 22 b may be dispersed in the polymer matrix 22 a. The polymermatrix 22 a may include, for example, at least one of polyvinylidenefluoride (PVDF), β-Polyvinylidene fluoride (β-PVDF),polyvinylidene-trifluoroethylene (PVDF-TrFE), rubber, polyurethane,polyethylene, PTFE, polypropylene, nylon, polycarbonate, polyimide,epoxy resin, and acrylic resin, but embodiments are not limited thereto.The piezoelectric material 22 b may be piezoelectric ceramic having aperovskite crystalline structure or a wurtzite crystalline structure,but embodiments are not limited thereto. The piezoelectric material 22 bmay include, for example, at least one of perovskite (CaTiO₃), bariumtitanate (BaTiO₃), lead zirconate titanate, (PZT) (PbZrTiO₃), quartz(SiO₂), strontium titanate (SrTiO₃), aluminum nitride (AlN), silveriodide (AgI), zinc oxide (ZnO), cadmium sulfide (CdS), cadmium selenide(CdSe), silicon carbide (α-SiC), gallium(III) nitride (GaN), and boronnitride (BN), but embodiments are not limited thereto.

The flexibility of the second structure 220 may be affected by thephysical properties of the polymer matrix 22 a, a size of the secondstructure 220, etc. For example, when a thickness of the secondstructure 220 is 300 μm or less, the second structure 220 may haveflexibility, and the thickness is not limited thereto. The flexibilityof the second structure 220 may be enhanced by adjusting a volume ratioof the polymer matrix 22 a and the piezoelectric material 22 b may beaffected by a size of the second structure 220, a thickness of thesecond structure 220, a product with the second structure 220 appliedthereto, and/or the like. For example, when the piezoelectric material22 b is formed of PZT and a volume ratio of PZT is 60%, the young'smodulus of the second structure 220 may be 5.1 GPa. Accordingly, thepolymer matrix 22 a may have a volume ratio of 40%, and thepiezoelectric material 22 b may have a volume ratio of 60%. In thiscase, the flexibility of the second structure 220 may be enhanced.

The first structure 240 may include a first part 24 a and a second part24 b disposed between adjacent first parts 24 a. The first part 24 a mayinclude an inorganic material part, and the second part 24 b may includean organic material part. The first structure is as described above withreference to FIGS. 5A to 10B, and thus, their detailed descriptions areomitted.

The sound generating device may include a first electrode 211 disposedover the first structure 240, a second electrode 212 disposed under thefirst structure 240, and a third electrode 213 disposed over the secondstructure 220. The first electrode 211, the second electrode 212, andthe third electrode 213 may apply a voltage to the first structure 240and the second structure 220. For example, the second electrode 212 andthe third electrode 213 may be a positive (+) electrode, and the firstelectrode 211 may be a negative (−) electrode. As another example, thesecond electrode 212 and the third electrode 213 may be a negative (−)electrode, and the first electrode 211 may be a positive (+) electrode.For example, the first electrode 211, the second electrode 212, and thethird electrode 213 may include one or more of carbon (C), palladium(Pd), iron (Fe), tin (Sn), aluminum (Al), nickel (Ni), platinum (Pt),gold (Au), silver (Ag), copper (Cu), titanium (Ti), and molybdenum (Mo),or an alloy thereof, but embodiments are not limited thereto. Forexample, the first electrode 211, the second electrode 212, and thethird electrode 213 may include indium tin oxide (ITO) or amolybdenum-titanium alloy (a Mo—Ti alloy), but embodiments are notlimited thereto.

When an alternating current (AC) voltage is applied to the firstelectrode 211, the second electrode 212, and the third electrode 213 ofthe sound generating device 700, the first structure 240 and the secondstructure 220 may alternately and repeatedly expand and contract,thereby generating a vibration based on a bending phenomenon where abending direction is alternately changed. The display panel 100 mayvibrate based on the generated vibration to generate a sound. Thedisplay panel 100 may vibrate with kinetic energy based on polarizationwhich is performed in a direction vertical to the display panel 100.Therefore, polarization performed in a vector direction except thedirection vertical to the display panel 100 may be lost. A wholevibration of the sound generating device 700 may be affected by summatedenergy in the vector direction vertical to the display panel 100, andthus, a polarization direction (illustrated by an arrow) of the firststructure 240 and a polarization direction (illustrated by an arrow) ofthe second structure 220 may be a direction vertical to the displaypanel 100. The display panel 100 may vibrate based on the expansion andcontraction of the first structure 240 and the second structure 220, andthus, when a polarization direction of the first structure 240 isopposite to that of the second structure 220, a sound pressure level ofthe sound generating device 700 may be enhanced. The second structure220 may form a polarization direction vertical to the display panel 100,and thus, the polarization direction of the first structure 240 may bealigned in a direction vertical to the display panel 100, therebyincreasing a vibration of the sound generating device 700. Accordingly,a sound pressure level of the sound generating device 700 may be moreenhanced.

A first passivation layer 201 may be disposed over the third electrode213, and a second passivation layer 202 may be disposed under the secondelectrode 212. When an external impact is applied, the first passivationlayer 201 and the second passivation layer 202 may protect the firststructure 240 and the second structure 220. For example, at least aportion of the first passivation layer 201 and the second passivationlayer 202 may have a non-flat shape. The first passivation layer 201 andthe second passivation layer 202 are as described above with referenceto FIG. 5A, and thus, their detailed descriptions are omitted. Also,FIG. 12 may be applied to a sound generating device to which thepassivation layers of FIGS. 5B to 6C are applied.

A size of the sound generating device 700 may be the same as that of thedisplay panel 100. Since the sound generating device 700 is configuredto secure a wide area corresponding to a size equal to that of thedisplay panel 100, a sound characteristic of a low sound band may beimproved compared to a film-type piezoelectric device, and a drivingvoltage may be reduced. For example, a size of the sound generatingdevice 700 may be 0.9 to 1.1 times a size of a display area AA of thedisplay panel 100, but embodiments are not limited thereto. Since a sizeof the sound generating device 700 is the same as or approximately equalto that of the display area AA of the display panel 100, the soundgenerating device 700 may cover a most region of the display panel 100,and a vibration generated by the sound generating device 700 may vibratea whole portion of the display panel 100, thereby enhancing a soundlocalization. Also, in a large-sized display apparatus, a whole portionof the large-sized display apparatus may vibrate, and thus, a soundlocalization may be more enhanced, thereby realizing a stereo soundeffect.

Therefore, since a sound generating device including a first structureand a second structure is implemented and passivation layers arerespectively provided over and under an electrode, a sound pressurelevel of the sound generating device 700 may be more enhanced, therebydecreasing an impact applied to the sound generating device 700 when anexternal impact is applied thereto.

FIGS. 13A and 13B are diagrams illustrating a display apparatusincluding a sound generating device according to an embodiment of thepresent disclosure.

With reference to FIG. 13A, a display apparatus 80 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 700. The sound generating device 700 mayinclude a first structure 240 and a second structure 220. The soundgenerating device 700 may include a first electrode 211 disposed overthe first structure 240, a second electrode 212 disposed under the firststructure 240, and a third electrode 213 disposed over the secondstructure 220. The sound generating device 700 may vibrate the displaypanel 100 to generate a sound SW. For example, the sound generatingdevice 700 may directly vibrate the display panel 100 to output thesound SW to a forward region in front of the display panel 100. Thefirst structure 240 and the second structure 220 are as described abovewith reference to FIGS. 5A to 10B and 12, and thus, their detaileddescriptions are omitted. An adhesive may be further provided betweenthe first passivation layer 201 and the third electrode 213, and anadhesive may be further provided between the second passivation layer202 and the second electrode 212. The adhesive may be, for example, anacrylic adhesive, an epoxy-based adhesive, and a silicon-based adhesive,and a functional group may be added to the adhesive to improve anadhesive force or a manufacturing process. However, embodiments are notlimited thereto. Also, in order to improve an adhesive force to thefirst and second passivation layers 201 and 202 and/or enhance anelastic modulus suitable for the second electrode 212 or the thirdelectrode 213, the adhesive may be used in common or mixed, or athickness of the adhesive may be differently adjusted. However,embodiments are not limited thereto.

A young's modulus of the second structure 220 may be less than that ofthe first structure 240. For example, the young's modulus of the secondstructure 220 may be 1 GPa or less, and a young's modulus of the firststructure 240 may be less than 50 GPa. The second structure 220 having alow young's modulus may be disposed more adjacent to the display panel100 than the first structure 240, and thus, an external impact may bereduced by the second structure 220. Accordingly, the second structure220 may be disposed more adjacent to the display panel 100 than thefirst structure 240, thereby providing a display apparatus with enhancedimpact resistance and flexibility.

With reference to FIG. 13B, a display apparatus 90 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 700. The sound generating device 700 mayinclude a first structure 240 and a second structure 220. The secondstructure 220 may be disposed more adjacent to the display panel 100than the first structure 240. The sound generating device 700 mayinclude the second structure 220, thereby providing a display apparatuswith enhanced impact resistance and flexibility. Therefore, the soundgenerating device 700 may have flexibility, and thus, may be applied toa flexible display apparatus. A foldable display apparatus isillustrated as an example of the display apparatus 90. For example, anexample where the display panel 100 is outward folded is illustrated.When the display panel 100 is folded outward, a compressive stress maybe released by the second structure 220 of the sound generating device700 and may be transferred to the first structure 240, thereby providinga display apparatus with enhanced flexibility. Also, the secondstructure 220 of the sound generating device 700 may absorb impactenergy against an external impact applied to the display panel 100 andmay transfer remaining energy to the first structure 240, therebyproviding a display apparatus with secured impact resistance. When thesound generating device 700 is applied to a foldable display apparatus,the display panel 100 may have a certain curvature radius in onedirection, and the sound generating device 700 may be bent correspondingto a curvature of the display panel 100. As another example, the soundgenerating device 700 according to an embodiment of the presentdisclosure may be applied to a bendable or rollable display apparatus.

FIG. 14 is a diagram illustrating a sound generating device according toan embodiment of the present disclosure.

With reference to FIG. 14, a first structure 240 of a sound generatingdevice 800 according to an embodiment of the present disclosure may bedisposed over a second structure 220. The sound generating device 800may include a first electrode 211 disposed over the first structure 240,a second electrode 212 disposed under the first structure 240, and afourth electrode 214 disposed under the second structure 220. The firstelectrode 211, the second electrode 212, and the fourth electrode 214may apply a voltage to the first structure 240 and the second structure220. For example, the first electrode 211 and the fourth electrode 214may be a negative (−) electrode, and the second electrode 212 may be apositive (+) electrode. As another example, the first electrode 211 andthe fourth electrode 214 may be a positive (+) electrode, and the secondelectrode 212 may be a negative (−) electrode. For example, the firstelectrode 211, the second electrode 212, and the fourth electrode 214may include one or more of carbon (C), palladium (Pd), iron (Fe), tin(Sn), aluminum (Al), nickel (Ni), platinum (Pt), gold (Au), silver (Ag),copper (Cu), titanium (Ti), and molybdenum (Mo), or an alloy thereof,but embodiments are not limited thereto. For example, the firstelectrode 211, the second electrode 212, and the third electrode 213 mayinclude ITO or a Mo—Ti alloy, but embodiments are not limited thereto.

When an AC voltage is applied to the first electrode 211, the secondelectrode 212, and the fourth electrode 214 of the sound generatingdevice 800, the first structure 240 and the second structure 220 mayalternately and repeatedly expand and contract, thereby generating avibration based on a bending phenomenon where a bending direction isalternately changed. The display panel 100 may vibrate based on thegenerated vibration to generate a sound. The display panel 100 mayvibrate with kinetic energy based on polarization which is performed ina direction vertical to the display panel 100. Therefore, polarizationperformed in a vector direction except the direction vertical to thedisplay panel 100 may be lost. A whole vibration of the sound generatingdevice 800 may be affected by summated energy in the vector directionvertical to the display panel 100, and thus, a polarization direction(illustrated by an arrow) of the first structure 240 and a polarizationdirection (illustrated by an arrow) of the second structure 220 may be adirection vertical to the display panel 100. The display panel 100 mayvibrate based on the expansion and contraction of the first structure240 and the second structure 220, and thus, when a polarizationdirection of the first structure 240 is opposite to that of the secondstructure 240, a sound pressure level of the sound generating device 800may be enhanced. The sound generating device 800 may be configured bythe first structure 240 and the second structure 220, the secondstructure 220 may form a polarization direction vertical to the displaypanel 100, and the polarization direction of the first structure 240 maybe aligned in a direction vertical to the display panel 100, therebyincreasing a vibration of the sound generating device 800. Accordingly,a sound pressure level of the sound generating device 800 may be moreenhanced. Therefore, in the sound generating device 800 according to anembodiment of the present disclosure, since a polarization directionvertical to the display panel 100 is formed by the first structure 240,a sound characteristic may be secured, and a flexible characteristic maybe secured by the second structure 220, thereby providing a displayapparatus with enhanced sound characteristic and flexibility.

A first passivation layer 201 may be disposed over the first electrode211, and a second passivation layer 202 may be disposed under the fourthelectrode 214. When an external impact is applied, the first passivationlayer 201 and the second passivation layer 202 may protect the firststructure 240 and the second structure 220. For example, at least aportion of the first passivation layer 201 and the second passivationlayer 202 may have a non-flat shape. The first passivation layer 201 andthe second passivation layer 202 are as described above with referenceto FIG. 5A, and thus, their detailed descriptions are omitted. Also,FIG. 14 may be applied to a sound generating device to which thepassivation layers of FIGS. 5B to 6C are applied.

A size of the sound generating device 800 may be the same as that of thedisplay panel 100. Since the sound generating device 800 is configuredto secure a wide area corresponding to a size equal to that of thedisplay panel 100, a sound characteristic of a low sound band may beimproved compared to a film-type piezoelectric device, and a drivingvoltage may be reduced. For example, a size of the sound generatingdevice 800 may be 0.9 to 1.1 times a size of a display area AA of thedisplay panel 100, but embodiments are not limited thereto. Since a sizeof the sound generating device 800 is the same as or approximately equalto that of the display area AA of the display panel 100, the soundgenerating device 800 may cover a most region of the display panel 100,and a vibration generated by the sound generating device 800 may vibratea whole portion of the display panel 100, thereby enhancing a soundlocalization. Also, in a large-sized display apparatus, a whole portionof the large-sized display apparatus may vibrate, and thus, a soundlocalization may be more enhanced, thereby realizing a stereo soundeffect.

Therefore, since a sound generating device includes a first structurehaving a piezoelectric characteristic and a second structure having animpact resistance and flexibility, the impact resistance and flexibilityof the sound generating device may be secured. Accordingly, a displayapparatus having an excellent vibration characteristic and an excellentsound characteristic may be provided. Also, since a sound generatingdevice including a first structure and a second structure is implementedand passivation layers are respectively provided over and under anelectrode, a sound pressure level of the sound generating device may bemore enhanced, thereby decreasing an impact applied to the soundgenerating device when an external impact is applied thereto.

FIGS. 15A to 15C are diagrams illustrating a display apparatus includinga sound generating device according to an embodiment of the presentdisclosure.

With reference to FIG. 15A, a display apparatus 110 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 800. The sound generating device 800 mayinclude a first structure 240 and a second structure 220. The soundgenerating device 800 may include a first electrode 211 disposed overthe first structure 240, a second electrode 212 disposed under the firststructure 240, and a fourth electrode 214 disposed under the secondstructure 220. The sound generating device 800 may vibrate the displaypanel 100 to generate a sound SW. For example, the sound generatingdevice 800 may directly vibrate the display panel 100 to output thesound SW to a forward region in front of the display panel 100. Thefirst structure 240 and the second structure 220 are as described abovewith reference to FIGS. 5A to 10B and 14, and thus, their detaileddescriptions are omitted. An adhesive may be further provided betweenthe first passivation layer 201 and the first electrode 211, and anadhesive may be further provided between the second passivation layer202 and the fourth electrode 214. The adhesives may be, for example, anacrylic adhesive, an epoxy-based adhesive, and a silicon-based adhesive,and a functional group may be added to the adhesive so as to improve anadhesive force or a manufacturing process. However, embodiments are notlimited thereto. Also, in order to improve an adhesive force to thefirst and second passivation layers 201 and 202 and/or enhance anelastic modulus suitable for the first electrode 211 or the fourthelectrode 214, the adhesive may be used in common or mixed, or athickness of the adhesive may be differently adjusted. However,embodiments are not limited thereto.

The first structure 240 may be disposed more adjacent to the displaypanel 100 than the second structure 220. Therefore, a vibrationgenerated by the first structure 240 may be directly transferred to thedisplay panel 100, and the loss of a vibration needed for generating asound pressure may be minimized, thereby easily securing a soundpressure level suitable for a speaker. Also, since the loss of avibration is minimized, an efficiency of generating a sound pressure mayincrease, and thus, a voltage applied to the sound generating device 800may be reduced, thereby decreasing power consumption. Accordingly, thesound generating device 800 may have flexibility by using the secondstructure 220, thereby providing a sound generating device with enhancedflexibility and sound pressure level.

With reference to FIG. 15B, a display apparatus 120 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 800. In a sound generating device using avoice coil or a piezoelectric ceramic, it is difficult to apply thesound generating device to a flexible display apparatus. For example, ina case where a voice coil or a piezoelectric ceramic is applied to asound generating device, a separate structure may be needed for applyingthe sound generating device to a flexible display apparatus, and due tothis, since a thickness of a display apparatus is thickened or aflexible characteristic is limited to a certain level or less, a problemof a material should be solved. The sound generating device 800according to an embodiment of the present disclosure may haveflexibility, and thus, may be applied to a flexible display apparatus. Afoldable display apparatus is illustrated as an example of the displayapparatus 120. For example, an example where the display apparatus 50 isfolded outward from the display panel 100 is illustrated. A compressivestress which occurs when the display apparatus 120 is folded outwardfrom the display panel 100 may be transferred to a second structure 220through a first structure 240. A compression deformation rate based onthe compressive stress which occurs when the display apparatus 120 isfolded outward from the display panel 100 may increase in a directiondistancing from the display panel 100 corresponding to a point at whichthe compressive stress occurs, and thus, the compressive stress may bemore efficiently released by the second structure 220 havingflexibility, thereby providing a display apparatus with more enhancedflexibility.

With reference to FIG. 15C, an example where a display apparatus 130according to an embodiment of the present disclosure is folded inwardfrom a display panel 100 is illustrated. An expansive stress whichoccurs when the display apparatus 130 is folded inward from the displaypanel 100 may be transferred to a second structure 220 through a firststructure 240. An expansion deformation rate based on the expansivestress which occurs when the display apparatus 130 is folded inward fromthe display panel 100 may increase in a direction distancing from thedisplay panel 100 corresponding to a point at which the expansive stressoccurs, and thus, the expansive stress may be more efficiently releasedby the second structure 220 having flexibility, thereby providing adisplay apparatus with more enhanced flexibility. In a case where asound generating device is applied to a foldable display apparatus, thedisplay panel 100 may have a certain curvature radius in one direction,and the sound generating device may be bent correspondingly to acurvature of the display panel 100. As another example, a soundgenerating device 800 according to an embodiment of the presentdisclosure may be applied to a bendable or rollable display apparatus.Accordingly, a display apparatus with enhanced flexibility and soundpressure level may be provided.

As described above with reference to FIGS. 12 to 15C, in a case where asound generating device including a first structure and a secondstructure is provided, an impact resistance and flexibility may besecured, and flexibility and a sound pressure level may be enhanced. Forexample, in a case where a display apparatus is configured with thesound generating device of FIGS. 12 to 13B, an impact resistance andflexibility may be secured, and in a case where a display apparatus isconfigured with the sound generating device of FIGS. 14 to 15C,flexibility and a sound pressure level may be enhanced. Therefore, theinventors have performed various experiments for implementing a soundgenerating device for enhancing an impact resistance, flexibility, and asound pressure level. This will be described below with reference toFIGS. 14 to 19B.

FIG. 16 is a diagram illustrating a sound generating device according toan embodiment of the present disclosure, and FIG. 17 is a diagramillustrating a display apparatus including a sound generating deviceaccording to an embodiment of the present disclosure.

With reference to FIGS. 16 and 17, a display apparatus 140 according toan embodiment of the present disclosure may include a display panel 100and a sound generating device 900. The sound generating device 900 mayinclude a first structure 240, a second structure 220, and a thirdstructure 280. The first structure and the second structure are asdescribed above with reference to FIGS. 5A to 10B and 12 to 13B, andthus, their detailed descriptions are omitted or will be briefly givenbelow. A first passivation layer 201 and a second passivation layer 202are as described above with reference to FIG. 5A, and thus, theirdetailed descriptions are omitted. Also, FIG. 16 may be applied to asound generating device to which the passivation layers of FIGS. 5B to6C are applied.

When the second structure 220 is provided more adjacent to the displaypanel 100 than the first structure 240, an impact resistance andflexibility may be enhanced by the second structure 220. In such astructure, a sound pressure level may not be secured. Therefore, theinventors have performed various experiments for placing a thirdstructure so as to more enhance a sound pressure level of a soundgenerating device. In order to more enhance the sound pressure level ofthe sound generating device, the third structure 280 may be disposedover the second structure 220, and the third structure 280 may bedisposed to have the same configuration as that of the first structure240. The third structure 280 may be disposed over the second structure220. As another example, the third structure 280 may be disposed underor over the first structure 240. The third structure 280 may be disposedto have the same configuration as that of the first structure 240. Forexample, the third structure 280 may include a first part 28 a and asecond part 28 b disposed between adjacent first parts 28 a. The firstpart 28 a may include an inorganic material part, and the second part 28b may include an organic material part. The sound generating device 900may vibrate the display panel 100 to generate a sound SW. For example,the sound generating device 900 may directly vibrate the display panel100 to output the sound SW to a forward region in front of the displaypanel 100. Therefore, since the third structure 280 is further provided,a vibration generated by the third structure 280 may be directlytransferred to the display panel 100, and the loss of a vibration neededfor generating a sound pressure may be minimized, thereby easilysecuring a sound pressure level suitable for a speaker. Also, since theloss of a vibration is minimized, an efficiency of generating a soundpressure may increase, and thus, a voltage applied to the soundgenerating device 900 may be reduced, thereby decreasing powerconsumption.

The sound generating device 900 may include a first electrode 211disposed over the first structure 240, a second electrode 212 disposedunder the first structure 240, a third electrode 213 disposed over thesecond structure 220, and a fourth electrode 214 disposed over the thirdstructure 280. An adhesive may be further provided between the firstpassivation layer 201 and the fourth electrode 214, and an adhesive maybe further provided between the second passivation layer 202 and thesecond electrode 212. The adhesives may be, for example, an acrylicadhesive, an epoxy-based adhesive, and a silicon-based adhesive, and afunctional group may be added to the adhesive to improve an adhesiveforce or a manufacturing process. However, embodiments are not limitedthereto. Also, in order to improve an adhesive force to the first andsecond passivation layers 201 and 202 and/or enhance an elastic modulussuitable for the second electrode 212 or the fourth electrode 214, theadhesive may be used in common or mixed, or a thickness of the adhesivemay be differently adjusted. However, embodiments are not limitedthereto.

The first electrode 211, the second electrode 212, the third electrode213, and the fourth electrode 214 may apply a voltage to the firststructure 240, the second structure 220, and the third structure 280.For example, the first electrode 211 and the fourth electrode 214 may bea negative (−) electrode, and the second electrode 212 and the thirdelectrode 213 may be a positive (+) electrode. As another example, thefirst electrode 211 and the fourth electrode 214 may be a positive (+)electrode, and the second electrode 212 and the third electrode 213 maybe a negative (−) electrode. For example, the first electrode 211, thesecond electrode 212, the third electrode 213, and the fourth electrode214 may include one or more of carbon (C), palladium (Pd), iron (Fe),tin (Sn), aluminum (Al), nickel (Ni), platinum (Pt), gold (Au), silver(Ag), copper (Cu), titanium (Ti), and molybdenum (Mo), or an alloythereof, but embodiments are not limited thereto. For example, the firstelectrode 211, the second electrode 212, the third electrode 213, andthe fourth electrode 214 may include ITO or a Mo—Ti alloy, butembodiments are not limited thereto.

When an AC voltage is applied to the first electrode 211, the secondelectrode 212, the third electrode 213, and the fourth electrode 214 ofthe sound generating device 900, the first structure 240, the secondstructure 220, and the third structure 280 may alternately andrepeatedly expand and contract, thereby generating a vibration based ona bending phenomenon where a bending direction is alternately changed.The display panel 100 may vibrate based on the generated vibration togenerate a sound. The display panel 100 may vibrate with kinetic energybased on polarization which is performed in a direction vertical to thedisplay panel 100. Therefore, polarization performed in a vectordirection except the direction vertical to the display panel 100 may belost. A whole vibration of the sound generating device 900 may beaffected by summated energy in the vector direction vertical to thedisplay panel 100, and thus, a polarization direction (illustrated by anarrow) of the first structure 240, a polarization direction (illustratedby an arrow) of the second structure 220, and a polarization direction(illustrated by an arrow) of the third structure 280 may be a directionvertical to the display panel 100. The display panel 100 may vibratebased on the expansion and contraction of the first structure 240, thesecond structure 220, and the third structure 280, and thus, when apolarization direction of the second structure 220 is opposite to thatof the first structure 240 and the third structure 280, a sound pressurelevel of the sound generating device 900 may be enhanced. The firststructure 240 and the third structure 280 may form a polarizationdirection vertical to the display panel 100, and the polarizationdirection of the second structure 220 may be aligned in a directionvertical to the display panel 100, thereby increasing a vibration of thesound generating device 900. Accordingly, a sound pressure level of thedisplay apparatus 140 including the sound generating device 900 may bemore enhanced.

FIG. 18 is a diagram illustrating a sound generating device according toan embodiment of the present disclosure, and FIGS. 19A and 19B arediagrams illustrating a display apparatus including a sound generatingdevice according to an embodiment of the present disclosure.

With reference to FIGS. 18 and 19A, a display apparatus 150 according toan embodiment of the present disclosure may include a display panel 100and a sound generating device 1000. The sound generating device 1000 mayinclude a first structure 240, a second structure 220, and a thirdstructure 260. The first structure and the second structure are asdescribed above with reference to FIGS. 5A to 10B and 14 to 15C, andthus, their detailed descriptions are omitted or will be briefly givenbelow. A first passivation layer 201 and a second passivation layer 202are as described above with reference to FIG. 5A, and thus, theirdetailed descriptions are omitted. Also, FIG. 18 may be applied to asound generating device to which the passivation layers of FIGS. 5B to6C are applied.

When the first structure 240 is provided more adjacent to the displaypanel 100 than the second structure 220, a sound pressure may beenhanced by the first structure 240. In such a structure, a flexibilitylevel may not be secured. Therefore, the inventors have performedexperiments for placing a third structure so as to more enhance aflexibility of a sound generating device. In order to more enhance theflexibility of the sound generating device, the third structure may bedisposed over the first structure, and the third structure may bedisposed to have the same configuration as that of the second structure.For example, the third structure 260 may be disposed under or over thefirst structure 240. As another example, the third structure 260 may bedisposed under or over the second structure 220. The third structure 260may be disposed to have the same configuration as that of the secondstructure 220. For example, the third structure 260 may include apolymer matrix 26 a and a piezoelectric material 26 b included in thepolymer matrix 26 a. The piezoelectric material 26 b may be dispersed inthe polymer matrix 26 a. The sound generating device 1000 may vibratethe display panel 100 to generate a sound SW. For example, the soundgenerating device 1000 may directly vibrate the display panel 100 tooutput the sound SW to a forward region in front of the display panel100. Therefore, since the third structure 260 is further provided, asound generating device with more enhanced flexibility may be provided,thereby providing a display apparatus including a sound generatingdevice with enhanced impact resistance, flexibility, and sound pressurelevel.

The sound generating device 1000 may include a first electrode 211disposed over the first structure 240, a second electrode 212 disposedunder the first structure 240, a fourth electrode 214 disposed under thesecond structure 240, and a third electrode 213 disposed over the thirdstructure 260. An adhesive may be further provided between the firstpassivation layer 201 and the third electrode 213, and an adhesive maybe further provided between the second passivation layer 202 and thefourth electrode 214. The adhesives may be, for example, an acrylicadhesive, an epoxy-based adhesive, and a silicon-based adhesive, and afunctional group may be added to the adhesive to improve an adhesiveforce or a manufacturing process. However, embodiments are not limitedthereto. Also, to improve an adhesive force to the first and secondpassivation layers 201 and 202 and/or enhance an elastic modulussuitable for the third electrode 213 or the fourth electrode 214, theadhesive may be used in common or mixed, or a thickness of the adhesivemay be differently adjusted. However, embodiments are not limitedthereto.

The first electrode 211, the second electrode 212, the third electrode213, and the fourth electrode 214 may apply a voltage to the firststructure 240, the second structure 220, and the third structure 260.For example, the first electrode 211 and the fourth electrode 214 may bea negative (−) electrode, and the second electrode 212 and the thirdelectrode 213 may be a positive (+) electrode. As another example, thefirst electrode 211 and the fourth electrode 214 may be a positive (+)electrode, and the second electrode 212 and the third electrode 213 maybe a negative (−) electrode. For example, the first electrode 211, thesecond electrode 212, the third electrode 213, and the fourth electrode214 may include one or more of carbon (C), palladium (Pd), iron (Fe),tin (Sn), aluminum (Al), nickel (Ni), platinum (Pt), gold (Au), silver(Ag), copper (Cu), titanium (Ti), and molybdenum (Mo), or an alloythereof, but embodiments are not limited thereto. For example, the firstelectrode 211, the second electrode 212, the third electrode 213, andthe fourth electrode 214 may include ITO or a Mo—Ti alloy, butembodiments are not limited thereto.

When an AC voltage is applied to the first electrode 211, the secondelectrode 212, the third electrode 213, and the fourth electrode 214 ofthe sound generating device 1000, the first structure 240, the secondstructure 220, and the third structure 260 may alternately andrepeatedly expand and contract, thereby generating a vibration based ona bending phenomenon where a bending direction is alternately changed.The display panel 100 may vibrate based on the generated vibration togenerate a sound. The display panel 100 may vibrate with kinetic energybased on polarization which is performed in a direction vertical to thedisplay panel 100. Therefore, polarization performed in a vectordirection except the direction vertical to the display panel 100 may belost. A whole vibration of the sound generating device 1000 may beaffected by summated energy in the vector direction vertical to thedisplay panel 100, and thus, a polarization direction (illustrated by anarrow) of the first structure 240, a polarization direction (illustratedby an arrow) of the second structure 220, and a polarization direction(illustrated by an arrow) of the third structure 260 may be a directionvertical to the display panel 100. The display panel 100 may vibratebased on the expansion and contraction of the first structure 240, thesecond structure 220, and the third structure 260, and thus, when apolarization direction of the second structure 220 and the thirdstructure 260 is opposite to that of the first structure 240, a soundpressure level of the sound generating device 1000 may be enhanced. Thefirst structure 240 may form a polarization direction vertical to thedisplay panel 100, and the polarization direction of the secondstructure 220 and the third structure 260 may be aligned in a directionvertical to the display panel 100, thereby increasing a vibration of thesound generating device 1000. Accordingly, a sound pressure level of thesound generating device 1000 may be more enhanced. When the thirdstructure 260 is disposed more adjacent to the display panel 100 thanthe first structure 240, flexibility may be enhanced by the secondstructure 220 and the third structure 260, and an impact resistance maybe enhanced by the third structure 260. Accordingly, a display apparatusincluding a sound generating device with enhanced impact resistance,flexibility, and sound pressure level may be provided.

With reference to FIG. 19B, a display apparatus 160 according to anembodiment of the present disclosure may include a display panel 100 anda sound generating device 1000. The sound generating device 1000 is asdescribed above with reference to FIGS. 18 and 19A, and thus, itsdetailed description is omitted or will be briefly given below. In asound generating device using a voice coil or a piezoelectric ceramic,it is difficult to apply the sound generating device to a flexibledisplay apparatus. For example, in a case where a voice coil or apiezoelectric ceramic is applied to a sound generating device, aseparate structure may be needed for applying the sound generatingdevice to a flexible display apparatus, and due to this, since athickness of a display apparatus is thickened or a flexiblecharacteristic is limited to a certain level or less, a problem of amaterial should be solved. As described above with reference to FIGS. 18and 19A, the sound generating device 1000 according to an embodiment ofthe present disclosure may have an impact resistance and flexibility,and thus, may be applied to a flexible display apparatus. A foldabledisplay apparatus is illustrated as an example of the display apparatus160. An example where the display apparatus 160 is a foldable displayapparatus is illustrated. For example, an example where the displayapparatus 160 is folded inward from the display panel 100 isillustrated. In a case where a third structure 260 is disposed moreadjacent to the display panel 100 than a first structure 240, anexpansive stress may be released in the third structure 260 when thedisplay apparatus 160 is folded inward from the display panel 100 andmay be transferred to the first structure 240, thereby more securingflexibility. Therefore, flexibility may be enhanced by a secondstructure 220 and the third structure 260, and when an external impactis applied, the second structure 220 and the third structure 260 may actas a protection layer for the first structure 240, thereby enhancing animpact resistance of the sound generating device 1000. In FIG. 19B, anexample where a display panel is inward folded is illustrated, but thepresent embodiment may be applied to a display apparatus where a displaypanel is folded outward. When the display apparatus 160 is foldedoutward from the display panel 100, an compressive stress may bereleased in the second structure 220 and may be transferred to the firststructure 240, thereby more securing flexibility.

In a case where a display panel is folded inward, a bending area BA maybe bent to have a semicircular shape. A folded area may be the bendingarea BA. The bending area BA may be an area where a flexible substrateis bent. The flexible substrate may be formed of an insulating materialhaving flexibility. For example, the flexible substrate may be formed ofplastic such as polyimide, but embodiments are not limited thereto.Also, at least one back plate for supporting the flexible substrate maybe further provided under the flexible substrate. The back plate may beformed as a plastic thin film which is formed of polyimide, polyethylenenapthalate (PEN), polyethylene terephthalate (PET), other suitablepolymers, or a combination thereof, but embodiments are not limitedthereto. The flexible substrate may be configured so that the flexiblesubstrate is maintained in a flat state without being bent in an areaother than the bending area and only the bending area is bent.Therefore, the sound generating device 1000 may be disposed along thebending area BA and a display area AA. For example, the sound generatingdevice 1000 may be disposed to have a curved surface which is bentcorrespondingly to the bending area BA. When the display panel 100 has acertain curvature radius in one direction, the sound generating device1000 may be bent correspondingly to a curvature of the display panel100. When the sound generating device 1000 is applied to a rollabledisplay apparatus, the display panel 100 may be wound or unwound, thesound generating device 1000 may be disposed based on winding orunwinding of the display panel 100. Therefore, the sound generatingdevice according to an embodiment of the present disclosure may beapplied to a plastic electroluminescent display apparatus, a flexibledisplay apparatus, a bendable display apparatus, a foldable displayapparatus, a rollable display apparatus, etc. As another example, thesound generating device according to an embodiment of the presentdisclosure may be applied to a wearable display apparatus.

FIG. 20 is a diagram showing a sound output characteristic of a soundgenerating device according to an embodiment of the present disclosure.

In FIG. 20, the abscissa axis represents a frequency (Hz), and theordinate axis represents a sound pressure level (SPL) (dB). A soundoutput characteristic has been measured in an anechoic chamber which isclosed in all directions, and measurement equipment has used AudioPrecision company's APX525. Measurement has been performed under acondition where a driving voltage is 10.6 Vrms and a sound pressurelevel measurement distance to a center of a sound generating module isabout 5 cm. An applied frequency signal has been applied as a sine sweepwithin a range of 200 Hz to 20 kHz, and ⅓ octave smoothing has beenperformed on a measurement result. A measurement method is not limitedthereto.

In FIG. 20, a dot line represents a display apparatus to which FIG. 3 isapplied, a one-dot-dashed line represents a display apparatus (FIG. 5A)to which the sound generating device 200 according to an embodiment ofthe present disclosures is applied, and a solid line represents adisplay apparatus (FIG. 6A) to which the sound generating device 500according to an embodiment of the present disclosures is applied.Measurement has been performed under a condition where an electrode isformed a Mo—Ti alloy, a passivation layer is formed of polyimide, thefirst part 24 a of the first structure 240 is formed of a PZT-basedmaterial, and the second part 24 b is formed of an epoxy-based polymer,but embodiments are not limited thereto. Even when FIGS. 5B, 5C, 6B, 6C,11, 13A, 13B, 15A to 15C, 17, 19A, and 19B are applied, the same resultor a similar result may be obtained as a sound output characteristic.

With reference to FIG. 20, comparing with a display apparatus whichincludes a passivation layer including a plurality of concave portionsand a passivation layer including a plurality of convex portions and aplurality of concave portions, it may be seen that a sound pressurelevel is low in a whole frequency domain when a passivation layeraccording to an embodiment of the present disclosure is not applied.Comparing with a case where a passivation layer including a plurality ofconcave portions is applied, it may be seen that a sound is enhancedwhen a passivation layer including a plurality of convex portions and aplurality of concave portions is applied. Comparing with a case whereFIG. 3 is applied, in a case where the sound generating device 200according to an embodiment of the present disclosure is applied, it maybe seen that a sound pressure level is enhanced in a frequency domain ofabout 0.2 kHz or higher, and it may be seen that a sound pressure levelincrease by about 10 dB or more in a frequency band of 1 kHz to 3 kHzoccupying a large part of frequency band in an audible sound of a soundgenerating device which is a speaker. Comparing with a case where FIG. 3is applied, in a case where the sound generating device 500 according toan embodiment of the present disclosure is applied, it may be seen thata sound pressure level is enhanced in a frequency domain of about 0.2kHz or higher, it may be seen that a sound pressure level increase byabout 10 dB or more in a frequency band of 1 kHz to 3 kHz occupying alarge part of frequency band in an audible sound of a sound generatingdevice which is a speaker, and since a sound pressure level increase byabout 10 dB or more in a low frequency domain of 200 Hz to 500 Hzcorresponding to a drawback of a piezoelectric speaker, it may be seenthat a total sound pressure characteristic is enhanced. Comparing with acase where the sound generating device 200 according to an embodiment ofthe present disclosure is applied, in a case where the sound generatingdevice 500 according to an embodiment of the present disclosure isapplied, it may be seen that a sound pressure level increase by about 5dB to about 12 dB in a low frequency domain of 200 Hz to 500 Hzcorresponding to a drawback of a piezoelectric speaker, and thus, atotal sound pressure characteristic is enhanced. Therefore, the soundgenerating device according to an embodiment of the present disclosuremay have an excellent vibration characteristic for enhancing a soundpressure level in a whole frequency domain, thereby providing a soundgenerating device having flexibility and an impact resistance. Also, thesound generating device according to an embodiment of the presentdisclosure may enhance a sound pressure level in a whole frequencydomain, thereby providing a sound generating device capable of beingapplied to a display apparatus.

A sound generating device according to an embodiment of the presentdisclosure may be applied as a sound generating device in a displayapparatus. A display apparatus according to an embodiment of the presentdisclosure may be applied to mobile apparatuses, video phones, smartwatches, watch phones, wearable apparatuses, foldable apparatuses,rollable apparatuses, bendable apparatuses, flexible apparatuses, curvedapparatuses, portable multimedia players (PMPs), personal digitalassistants (PDAs), electronic organizers, desktop personal computers(PCs), laptop PCs, netbook computers, workstations, navigationapparatuses, automotive navigation apparatuses, automotive displayapparatuses, TVs, wall paper display apparatuses, signage apparatuses,game machines, notebook computers, monitors, cameras, camcorders, homeappliances, etc. Also, the sound generating device according to anembodiment of the present disclosure may be applied to organic lightemitting lighting apparatuses or inorganic light emitting lightingapparatuses. When the sound generating device is applied to a lightingapparatus, the sound generating device may act as lighting and aspeaker.

A display apparatus according to an embodiment of the present disclosurewill be described below.

According to an embodiment of the present disclosure, a displayapparatus includes a display panel configured to display an image and asound generating device on a rear surface of the display panel, thesound generating device being configured to vibrate the display panel togenerate sound, wherein the sound generating device includes a firststructure and a first passivation layer on one side of the firststructures, at least a portion of the first passivation layer having anon-flat shape.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the first structure may include a first part havinga piezoelectric characteristic and a second part between adjacent firstparts to have flexibility.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a second passivation layer on theother side of the first structure, at least a portion of the secondpassivation layer having a non-flat shape.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the non-flat shape may include a plurality ofconcave portions, or a plurality of concave portions and a plurality ofconvex portions.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the plurality of concave portions and the pluralityof convex portions of the first passivation layer and the plurality ofconcave portions and the plurality of convex portions of the secondpassivation layer may be arranged in zigzag.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the first structure may include an inorganicmaterial part and an organic material part between adjacent inorganicmaterial parts.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the plurality of concave portions may correspond tothe inorganic material part, or may correspond to the inorganic materialpart and the organic material part.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the plurality of concave portions and the pluralityof convex portions may be disposed correspondingly to the inorganicmaterial part and the organic material part.

For example, in a display apparatus according to an embodiment of thepresent disclosure, each of the plurality of concave portions maycorrespond to at least two inorganic material parts and an organicmaterial part between the at least two inorganic material parts, andeach of the plurality of convex portions may correspond to at least twoinorganic material parts and an organic material part between the atleast two inorganic material parts.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a second structure over or underthe first structure, the second structure including a polymerpiezoelectric material.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a third structure over the secondstructure, the third structure being the same as the first structure,wherein the second structure may be disposed more adjacent to thedisplay panel than the first structure.

For example, in a display apparatus according to an embodiment of thepresent disclosure, a polarization direction of the second structure maybe opposite to a polarization direction of the first structure and apolarization direction of the third structure.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a third structure over the firststructure, the third structure being the same as the second structure,wherein the first structure may be disposed more adjacent to the displaypanel than the second structure.

For example, in a display apparatus according to an embodiment of thepresent disclosure, a polarization direction of the first structure maybe opposite to a polarization direction of the second structure and apolarization direction of the third structure.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the first passivation layer may have an embossingshape including a plurality of concave portions and a plurality ofconvex portions using an embossing roller.

According to an embodiment of the present disclosure, a displayapparatus includes a display panel including a display area configuredto display an image and a non-display area surrounding the display areaand a sound generating device on a rear surface of the display panel,the sound generating device being configured to vibrate the displaypanel to generate sound, wherein the sound generating device includes afirst structure including a first part having a piezoelectriccharacteristic and a second part between adjacent first parts to haveflexibility and a passivation layer over or under the first structure,the passivation layer including a plurality of concave portions.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the first part may include an inorganic materialpart, and the second part may include an organic material part.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the plurality of concave portions may be disposedcorrespondingly to the first part, or may be disposed correspondingly tothe first part and the second part.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a plurality of convex portionsunder the plurality of concave portions, wherein the plurality ofconcave portions and the plurality of convex portions may be disposed tocorrespond to the first part and the second part.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a second structure over or underthe first structure, the second structure including a polymerpiezoelectric material.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a third structure over the secondstructure, the third structure being the same as the first structure,wherein the second structure may be disposed more adjacent to thedisplay panel than the first structure.

For example, in a display apparatus according to an embodiment of thepresent disclosure, a polarization direction of the second structure maybe opposite to a polarization direction of the first structure and apolarization direction of the third structure.

For example, a display apparatus according to an embodiment of thepresent disclosure may further include a third structure over the firststructure, the third structure being the same as the second structure,wherein the first structure may be disposed more adjacent to the displaypanel than the second structure.

For example, a display apparatus according to an embodiment of thepresent disclosure, a polarization direction of the first structure maybe opposite to a polarization direction of the second structure and apolarization direction of the third structure.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the non-display area may include a bending area, andthe sound generating device may be at the display area and the bendingarea and may include a curved surface along the bending area.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the display panel may have a certain curvatureradius, and the sound generating device may be bent based on a curvatureof the display panel.

For example, in a display apparatus according to an embodiment of thepresent disclosure, the display panel may be capable of being wound orunwound, and the sound generating device may be disposed to be wound orunwound based on winding or unwinding of the display panel.

According to an embodiment of the present disclosure, a sound generatingdevice includes a first structure including a first part having apiezoelectric characteristic and a second part between adjacent firstparts to have flexibility and a first passivation layer on one side ofthe first structure, at least a portion of the first passivation layerhaving a non-flat shape.

For example, a sound generating device according to an embodiment of thepresent disclosure further include a second passivation layer on theother side of the first structure, wherein at least a portion of thesecond passivation layer having a non-flat shape.

For example, in a sound in generating device according to an embodimentof the present disclosure, the non-flat shape may include a plurality ofconcave portions, or a plurality of concave portions and a plurality ofconvex portions.

For example, in a sound generating device according to an embodiment ofthe present disclosure, each of the plurality of concave portions maycorrespond to at least two first parts and a second part between the atleast two first parts, and each of the plurality of convex portions maycorrespond to at least two first parts and a second part between the atleast two first parts.

It will be apparent to those skilled in the art that variousmodifications and variations may be made in the display apparatus of thepresent disclosure without departing from the technical idea or scope ofthe disclosure. Thus, it is intended that embodiments of the presentdisclosure cover the modifications and variations of the disclosureprovided they come within the scope of the appended claims and theirequivalents.

1-28. (canceled)
 29. A sound generating device, comprising: a firststructure; and a first passivation layer on one side of the firststructure, at least a portion of the first passivation layer having anon-flat shape, wherein the first structure comprises: an inorganicmaterial part, and an organic material part between adjacent inorganicmaterial parts.
 30. The sound generating device of claim 29, wherein:the inorganic material part includes a piezoelectric characteristic; andthe organic material part includes flexibility.
 31. The sound generatingdevice of claim 29, wherein the non-flat shape comprises a plurality ofconcave portions, or a plurality of concave portions and a plurality ofconvex portions.
 32. The sound generating device of claim 29, furthercomprising a second passivation layer on the other side of the firststructure, at least a portion of the second passivation layer having anon-flat shape.
 33. The sound generating device of claim 32, wherein thenon-flat shape of the first passivation layer and the second passivationlayer comprises a plurality of concave portions, or a plurality ofconcave portions and a plurality of convex portions.
 34. The soundgenerating device of claim 33, wherein the plurality of concave portionsand the plurality of convex portions of the first passivation layer andthe plurality of concave portions and the plurality of convex portionsof the second passivation layer are arranged in zigzag.
 35. The soundgenerating device of claim 34, wherein the plurality of concave portionscorrespond to the inorganic material part, or correspond to theinorganic material part and the organic material part.
 36. The soundgenerating device of claim 34, wherein the plurality of concave portionsand the plurality of convex portions are disposed correspondingly to theinorganic material part and the organic material part.
 37. The soundgenerating device of claim 34, wherein: each of the plurality of concaveportions corresponds to: at least two inorganic material parts; and anorganic material part between the at least two inorganic material parts;and each of the plurality of convex portions corresponds to: at leasttwo inorganic material parts; and an organic material part between theat least two inorganic material parts.
 38. The sound generating deviceof claim 29, further comprising a second structure over or under thefirst structure, the second structure including a polymer piezoelectricmaterial.
 39. The sound generating device of claim 38, furthercomprising a third structure over the second structure, the thirdstructure being the same as the first structure.
 40. The soundgenerating device of claim 39, wherein a polarization direction of thesecond structure is opposite to a polarization direction of the firststructure and a polarization direction of the third structure.
 41. Thesound generating device of claim 38, further comprising a thirdstructure over the first structure, the third structure being the sameas the second structure.
 42. The sound generating device of claim 41,wherein a polarization direction of the first structure is opposite to apolarization direction of the second structure and a polarizationdirection of the third structure.
 43. The sound generating device ofclaim 29, wherein the first passivation layer has an embossing shapeincluding a plurality of concave portions and a plurality of convexportions using an embossing roller.
 44. A sound generating device,comprising: a first structure comprising: a first part having apiezoelectric characteristic; and a second part between adjacent firstparts to have flexibility; and a passivation layer over or under thefirst structure, the passivation layer including a plurality of concaveportions, wherein the first part comprises an inorganic material part,and wherein the second part comprises an organic material part.
 45. Thesound generating device of claim 44, wherein the plurality of concaveportions are disposed correspondingly to the first part, or are disposedcorrespondingly to the first part and the second part.
 46. The soundgenerating device of claim 44, further comprising: the passivation layerunder the first structure; and a plurality of convex portions under theplurality of concave portions, wherein the plurality of concave portionsand the plurality of convex portions are disposed correspondingly to thefirst part and the second part.
 47. The sound generating device of claim44, further comprising a second structure over or under the firststructure, the second structure including a polymer piezoelectricmaterial.
 48. The sound generating device of claim 47, furthercomprising a display apparatus on the sound generating device, whereinthe display apparatus having a display area and a bending area; whereinthe sound generating device is at the display area and the bending area;and wherein the sound generating device comprises a curved surface alongthe bending area.
 49. The sound generating device of claim 47, furthercomprising: a display apparatus on the sound generating device, thedisplay apparatus having a certain curvature radius, wherein the soundgenerating device is bent based on a curvature of the display apparatus.50. The sound generating device of claim 47, further comprising: adisplay apparatus on the sound generating device, wherein the soundgenerating device is disposed to be wound or unwound based on winding orunwinding of the display apparatus.
 51. The sound generating device ofclaim 47, further comprising a third structure over the secondstructure, the third structure being the same as the first structure.52. The sound generating device of claim 51, wherein a polarizationdirection of the second structure is opposite to a polarizationdirection of the first structure and a polarization direction of thethird structure.
 53. The sound generating device of claim 51, furthercomprising: a display apparatus on the sound generating device, thedisplay apparatus comprising: a display area; and a bending area,wherein the sound generating device is at the display area and thebending area, and wherein the sound generating device comprises a curvedsurface along the bending area.
 54. The sound generating device of claim51, further comprising: a display apparatus on the sound generatingdevice, the display apparatus having a certain curvature radius, whereinthe sound generating device is bent based on a curvature of the displayapparatus.
 55. The sound generating device of claim 51, furthercomprising: a display apparatus on the sound generating device, whereinthe sound generating device is disposed to be wound or unwound based onwinding or unwinding of the display apparatus.
 56. The sound generatingdevice of claim 47, further comprising a third structure over the firststructure, the third structure being the same as the second structure.57. The sound generating device of claim 56, wherein a polarizationdirection of the first structure is opposite to a polarization directionof the second structure and a polarization direction of the thirdstructure.
 58. The sound generating device of claim 56, furthercomprising: a display apparatus on the sound generating device, thedisplay apparatus comprising: a display area; and a bending area,wherein the sound generating device is at the display area and thebending area, and wherein the sound generating device comprises a curvedsurface along the bending area.
 59. The sound generating device of claim56, further comprising: a display apparatus on the sound generatingdevice, the display apparatus having a certain curvature radius, whereinthe sound generating device is bent based on a curvature of the displayapparatus.
 60. The sound generating device of claim 56, furthercomprising: a display apparatus on the sound generating device, whereinthe sound generating device is disposed to be wound or unwound based onwinding or unwinding of the display apparatus.